Sample records for gallium alloys

  1. Microfluidic platforms for gallium-based liquid metal alloy

    NASA Astrophysics Data System (ADS)

    Kim, Daeyoung

    As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non-wetting property and became moveable by applying a magnetic field. Finally, using its metallic and liquid properties, microfluidic-based applications of gallium-based liquid metal alloy such as inkjet printing and reconfigurable photomask were investigated. A clog-free and oxide-free inkjet printing technique was developed by incorporating HCl-impregnated paper as orifice. Inkjet-printed liquid metal line can be used as a metallic interconnect even with significant deformation of the flexible substrate. Additionally, based on its ultraviolet light blocking property, a reconfigurable photolithography using gallium-based liquid metal alloy was demonstrated in a PDMS-based 7-segments microfluidic channel by showing single digit numbers ('0'˜'9') with attainable minimum feature size of 10 microm.

  2. Experimental evidence of Alfvn wave propagation in a Gallium alloy

    E-print Network

    Paris-Sud XI, Université de

    take a degenerate form, known as torsional waves and other quasi-geostrophic waves, and mayExperimental evidence of Alfvén wave propagation in a Gallium alloy Thierry Alboussière1, galinstan, are reported and show clear evidence of Alfvén wave propagation as well as resonance of Alfvén

  3. DOI: 10.1002/adfm.200701216 Eutectic Gallium-Indium (EGaIn): A Liquid Metal Alloy for

    E-print Network

    Prentiss, Mara

    DOI: 10.1002/adfm.200701216 Eutectic Gallium-Indium (EGaIn): A Liquid Metal Alloy for the Formation a study of the behavior of the electri- cally conductive fluid metal eutectic, gallium-indium (EGaIn, 75 This paper describes the rheological behavior of the liquid metal eutectic gallium-indium (EGa

  4. Thermodynamic properties of some gallium-based binary alloys

    Microsoft Academic Search

    O. E. Awe; Y. A. Odusote; O. Akinlade; L. A. Hussain

    2008-01-01

    We have studied the concentration dependence of the free energy of mixing, concentration–concentration fluctuations in the long-wavelength limit, the chemical short-range order parameter, the enthalpy and entropy of mixing of Ga–Zn, Ga–Mg and Al–Ga binary alloys at different temperatures using a quasi-chemical approximation for compound forming binary alloys and that for simple regular alloys. From the study of the thermodynamic

  5. Aluminum gallium nitride alloys and heterostructures: Growth, characterization and application

    NASA Astrophysics Data System (ADS)

    Li, Jing

    AlGaN alloys and heterostructures were grown by MOCVD and characterized by using Hall measurement, time-resolved photoluminescence (PL) and x-ray diffraction (XRD). Si-doped n-type AlxGa1-xN alloys with x up to 0.5 and Mg-doped p-type AlxGa1-xN alloys with x up to 0.27 were grown. Highly conductive n-type AlxGa 1-xN alloys were obtained for x up to 0.5. Emission lines of band-to-impurity transitions of free electrons with neutral Mg acceptors as well as localized excitons have been observed in the p-type AlxGa1-xN alloys. PL spectra showed that Mg acceptor activation energies EA increase with Al content and the results agrees with Hall measurement. Picosecond time-resolved PL was used to study the optical properties of GaN/AlxGa1-xN MQWs with varying structural parameters. The optimal GaN/AlxGa1-xN ( x ˜ 0.2) MQW structures for UV light emitter applications are those with well (barrier) widths ranging from 12 to 42 A (40 to 80 A). The decreased quantum efficiency in GaN/AlxGa1-xN MQWs with well width Lw < 12 A is due to the enhanced carrier leakage to the underlying GaN epilayers, while the decreased quantum efficiency in MQWs with well width Lw > 42 A is associated with an increased nonradiative recombination rate as Lw approaching the critical thickness of MQWs. InxAlyGa1-xN quaternary alloys were grown on sapphire substrates. The dominant optical transition at low temperatures in InxAlyGa1-xN quaternary alloys was due to localized exciton recombination, while the localization effects in InxAlyGa1-xN quaternary alloys were combined with those of InGaN and AlGaN ternary alloys with comparable In and Al compositions. We can achieve not only higher emission energies but also higher quantum efficiency in InxAlyGa1-x N quaternary alloys than that of GaN. AlN epilayers with high optical qualities have been grown on sapphire substrates by MOCVD. Band-edge emission lines have been observed both at low and room temperatures and are at 6.017 and 6.033 eV at 10 K Both the optical quality and the quantum efficiency of AlN epilayers are comparable to GaN. AlGaN/GaN-based heterostructure field-effect transistors (HFETs) by employing the delta-doped barrier and the SiO2 insulated-gate are fabricated and characterized. The device grown on sapphire substrate has a high drain-current-driving and gate-control capabilities as well as a very high gate-drain breakdown voltage of 200 V for a gate length of 1 mum and a source-drain distance of 3 mum. The incorporation of the SiO2 insulated-gate and the delta-doped barrier into HFET structures reduces the gate leakage and improves the 2D channel carrier mobility.

  6. Czochralski growth of gallium indium antimonide alloy crystals

    SciTech Connect

    Tsaur, S.C.

    1998-02-01

    Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform compositions up to nearly 5 mole% InSb.

  7. Measured iron-gallium alloy tensile properties under magnetic fields

    NASA Astrophysics Data System (ADS)

    Yoo, Jin-Hyeong; Flatau, Alison B.

    2004-07-01

    Tension testing is used to identify Galfenol material properties under low level DC magnetic bias fields. Dog bone shaped specimens of single crystal Fe100-xGax, where 17<=x<=33, underwent tensile testing along two crystalographic axis orientations, [110] and [100]. The material properties being investigated and calculated from measured quantities are: Young's modulus and Poisson's ratio. Data are presented that demonstrate the dependence of these material properties on applied magnetic field levels and provide a preliminary assessment of the trends in material properties for performance under varied operating conditions. The elastic properties of Fe-Ga alloys were observed to be increasingly anisotropic with rising Ga content for the stoichiometries examined. The largest elastic anisotropies were manifested in [110] Poisson's ratios of as low as -0.63 in one specimen. This negative Poisson's ratio creates a significant in-plane auxetic behavior that could be exploited in applications that capitalize on unique area effects produced under uniaxial loading.

  8. Alloying and Structure of Ultrathin Gallium Films on the (111) and (110) Surfaces of Palladium

    PubMed Central

    2013-01-01

    Growth, thermal stability, and structure of ultrathin gallium films on Pd(111) and Pd(110) are investigated by low-energy ion scattering and low-energy electron diffraction. Common to both surface orientations are growth of disordered Ga films at coverages of a few monolayers (T = 150 K), onset of alloy formation at low temperatures (T ? 200 K), and formation of a metastable, mostly disordered 1:1 surface alloy at temperatures around 400–500 K. At higher temperatures a Ga surface fraction of ?0.3 is slightly stabilized on Pd(111), which we suggest to be related to the formation of Pd2Ga bulk-like films. While on Pd(110) only a Pd-up/Ga-down buckled surface was observed, an inversion of buckling was observed on Pd(111) upon heating. Similarities and differences to the related Zn/Pd system are discussed. PMID:24089625

  9. Effect of microtextured surface topography on the wetting behavior of eutectic gallium-indium alloys.

    PubMed

    Kramer, Rebecca K; Boley, J William; Stone, Howard A; Weaver, James C; Wood, Robert J

    2014-01-21

    Liquid-embedded elastomer electronics have recently attracted much attention as key elements of highly deformable and "soft" electromechanical systems. Many of these fluid-elastomer composites utilize liquid metal alloys because of their high conductivities and inherent compliance. Understanding how these alloys interface with surfaces of various composition and texture is critical to the development of parallel processing technology, which is needed to create more complex and low-cost systems. In this work, we explore the wetting behaviors between droplets of gallium-indium alloys and thin metal films, with an emphasis on tin and indium substrates. We find that metallic droplets reactively wet thin metal foils, but the wettability of the foils may be tuned by the surface texture (produced by sputtering). The effects of both composition and texture of the substrate on wetting dynamics are quantified by measuring contact angle and droplet contact diameter as a function of time. Finally, we apply the Cassie-Baxter model to the sputtered and native substrates to gain insight into the behavior of liquid metals and the role of the oxide formation during interfacial processes. PMID:24358994

  10. Fabrication of magnetic nano liquid metal fluid through loading of Ni nanoparticles into gallium or its alloy

    NASA Astrophysics Data System (ADS)

    Xiong, Mingfeng; Gao, Yunxia; Liu, Jing

    2014-03-01

    In this study, Ni nanoparticles were loaded into the partially oxidized gallium and its alloys to fabricate desired magnetic nanofluid. It was disclosed that the Ni nanoparticles sharply increased the freezing temperature and latent heat of the obtained magnetic nano liquid metal fluid, while the melting process was less affected. For the gallium sample added with 10 vol% coated Ni particles, a hysteresis loop was observed and the magnetization intensity decreased with the increase of the temperature. The slope for the magnetization-temperature curve within 10-30 K was about 20 times of that from 40 K to 400 K. Further, the dynamic impact experiments of striking magnetic liquid metal droplets on the magnet revealed that the regurgitating of the leading edge of the liquid disk and the subsequent wave that often occurred in the gallium-indium droplets would disappear for the magnetic fluids case due to attraction force of the magnet.

  11. Ab initio study of gallium stabilized ?-plutonium alloys and hydrogen-vacancy complexes.

    PubMed

    Hernandez, Sarah C; Schwartz, Daniel S; Taylor, Christopher D; Ray, Asok K

    2014-06-11

    All-electron density functional theory was used to investigate ?-plutonium (?-Pu) alloyed with gallium (Ga) impurities at 3.125, 6.25, 9.375 atomic (at)% Ga concentrations. The results indicated that the lowest energy structure is anti-ferromagnetic, independent of the Ga concentration. At higher Ga concentrations (>3.125?at%), the position of the Ga atoms are separated by four nearest neighbor Pu-Pu shells. The results also showed that the lattice constant contracts with increasing Ga concentration, which is in agreement with experimental data. Furthermore with increasing Ga concentration, the face-centered-cubic structure becomes more stably coupled with increasing short-range disorder. The formation energies show that the alloying process is exothermic, with an energy range of -0.028 to -0.099?eV/atom. The analyses of the partial density of states indicated that the Pu-Ga interactions are dominated by Pu 6d and Ga 4p hybridizations, as well as Ga 4s-4p hybridizations. Finally, the computed formation energies for vacancy and hydrogen-vacancy complexes within the 3.125?at% Ga cell were 1.12?eV (endothermic) and -3.88?eV (exothermic), respectively. In addition, the hydrogen atom prefers to interact much more strongly to the Pu atom than the Ga atom in the hydrogen-vacancy complex. PMID:24832613

  12. Shear strain mediated magneto-electric effects in composites of piezoelectric lanthanum gallium silicate or tantalate and ferromagnetic alloys

    SciTech Connect

    Sreenivasulu, G.; Piskulich, E.; Srinivasan, G., E-mail: srinivas@oakland.edu [Physics Department, Oakland University, Rochester, Michigan 48409 (United States); Qu, P.; Qu, Hongwei [Electrical and Computer Engineering, Oakland University, Rochester, Michigan 48309 (United States); Petrov, V. M. [Institute of Electronic Information Systems, Novgorod State University, Veliky Novgorod (Russian Federation); Fetisov, Y. K. [Moscow State Technical University of Radio Engineering, Electronics and Automation, Moscow 19454 (Russian Federation); Nosov, A. P. [Institute of Metal Physics, Ural Division of Russian Academy of Sciences, 18 S. Kovalevskaya St, Ekaterinburg 620990 (Russian Federation)

    2014-07-21

    Shear strain mediated magneto-electric (ME) coupling is studied in composites of piezoelectric Y-cut lanthanum gallium silicate (LGS) or tantalate (LGT) and ferromagnetic Fe-Co-V alloys. It is shown that extensional strain does not result in ME effects in these layered composites. Under shear strain generated by an ac and dc bias magnetic fields along the length and width of the sample, respectively, strong ME coupling is measured at low-frequencies and at mechanical resonance. A model is discussed for the ME effects. These composites of Y-cut piezoelectrics and ferromagnetic alloys are of importance for shear strain based magnetic field sensors.

  13. Hydrostatic Pressure Effect on Molecular-Beam Epitaxy-Grown Indium Gallium Phosphide Alloys and Gallium Arsenide\\/indium Gallium Phosphide Quantum Well Structures

    Microsoft Academic Search

    Jianhui Chen

    1990-01-01

    The band structure of MBE-grown rm In_{x}Ga_{1-x}P alloys and GaAs\\/InGaP quantum well samples were studied using photoluminescence spectroscopy at 25 K under high pressures. The Gamma-band gap energies of the rm In_{x}Ga_ {1-x}P alloys at 25 K were measured to be 1.975 +\\/- 0.005, 1.924 +\\/- 0.005, and 1.882 +\\/- 0.005 eV for x = 0.48, 0.53, and 0.60 respectively.

  14. Gallium and gallium arsenide

    SciTech Connect

    Kramer, D.

    1988-01-01

    As part of the Nation's growing concern with the competitiveness of U.S. firms in the world economy, especially with respect to advanced materials, the Bureau of Mines assessed the actual and potential recovery and manufacturing capabilities for gallium and gallium arsenide (GaAs). GaAs has advanced from a laboratory curiosity to a material with important high-tech applications within only the last few years, and although protected North American gallium supplies are currently considered adequate, consumption could grow to the point that this assessment would need reevaluation.

  15. Iron-gallium alloys : temperature and field effects on [lambda]100 and magnetic anisotropy measurements

    E-print Network

    Lichter, Jenny, 1982-

    2004-01-01

    Magnetostriction measurements were taken on samples of Fe-Ga alloys (Galfenol) containing between 18% and 35% Ga in fields of 5 kOe to 24 kOe from room temperature to liquid nitrogen temperature. In addition, room temperature ...

  16. Influence of water on the interfacial behavior of gallium liquid metal alloys.

    PubMed

    Khan, Mohammad R; Trlica, Chris; So, Ju-Hee; Valeri, Michael; Dickey, Michael D

    2014-12-24

    Eutectic gallium indium (EGaIn) is a promising liquid metal for a variety of electrical and optical applications that take advantage of its soft and fluid properties. The presence of a rapidly forming oxide skin on the surface of the metal causes it to stick to many surfaces, which limits the ability to easily reconfigure its shape on demand. This paper shows that water can provide an interfacial slip layer between EGaIn and other surfaces, which allows the metal to flow smoothly through capillaries and across surfaces without sticking. Rheological and surface characterization shows that the presence of water also changes the chemical composition of the oxide skin and weakens its mechanical strength, although not enough to allow the metal to flow freely in microchannels without the slip layer. The slip layer provides new opportunities to control and actuate liquid metal plugs in microchannels-including the use of continuous electrowetting-enabling new possibilities for shape reconfigurable electronics, sensors, actuators, and antennas. PMID:25469554

  17. ISOTHERMAL (DELTA)/(ALPHA-PRIME) TRANSFORMATION AND TTT DIAGRAM IN A PLUTONIUM GALLIUM ALLOY

    SciTech Connect

    Oudot, B P; Blobaum, K M; Wall, M A; Schwartz, A J

    2005-11-11

    Differential scanning calorimetry (DSC) is used as an alternative approach to determining the tine-temperature-transformation (TTT) diagram for the martensitic delta to alpha-prime transformation in a Pu-2.0 at% Ga alloy. Previous work suggests that the TTT diagram for a similar alloy exhibits an unusual double-C curve for isothermal holds of less than 100 minutes. Here, we extend this diagram to 18 hours, and confirm the double-C curve behavior. When the sample is cooled prior to the isothermal holds, the delta to alpha-prime transformation is observed as several overlapping exothermic peaks. These peaks are very reproducible, and they are believed to be the result of different kinds of delta to alpha-prime martensitic transformation. This may be due to the presence of different nucleation sites and/or different morphologies.

  18. Native point defects in indium nitride and indium-rich indium gallium nitride alloys

    NASA Astrophysics Data System (ADS)

    Li, Sonny Xiao-Zhe

    The recent discovery of the narrow bandgap of InN of 0.7 eV has attracted strong scientific interests on the fundamental properties and possible applications of InN and its ternary alloys. The first part of this thesis was inspired by the proposal of using InxGa1-x N alloy to build high efficiency solar cell for space applications. To test the irradiation hardness of InN and InxGa 1-xN, we have irradiated numerous samples with energetic particles (1-2 MeV electrons, protons, and 4He+ particles). InN and InxGa1-xN displayed superior radiation hardness over current multi-junction solar cell materials such as GaAs and GaInP in terms of electronic and optical properties. Free electron concentrations in InN and In-rich InxGa 1-xN increased with irradiation dose but saturated at a sufficiently high damage dose. According to the amphoteric defect model, the doping effect and the electron concentration saturation originates from irradiation-induced native donors and Fermi level pinning at the Fermi level stabilization energy (EFS). The EFS, an average energy of all localized native defects, dictates the electronic properties (donor or acceptor) of the native point defects. The electron concentration saturation and Fermi level pinning lead to profound changes in the optical properties. Absorption spectra shift to higher energy due to the conduction band-filling effect (Burstein-Moss shift). Photoluminescence (PL) signals broadened and shifted to higher energy as the k-conservation rule collapsed with irradiation damage. The PL intensity of increased slightly with higher carrier concentration before it became quenched by the irradiation-induced carrier traps. Capacitance-voltage (CV) measurements show that the pinning of the surface Fermi energy at EFS is also responsible for the surface electron accumulation effect in InN and In-rich In xGa1-xN alloys. The second part of this thesis focuses on the hydrostatic pressure dependence of group III-nitride alloys. The hydrostatic pressure dependence of the narrow bandgap of InN, In-rich InxGa1-x N (0 < x ? 0.5), and InyAl 1-yN (y = 0.25) alloys was measured by optical absorption and PL experiments with samples mounted in diamond anvil cells. The pressure coefficient of InN was experimentally determined for the first time to be 3.0+/-0.1 meV/kbar. The PL signal exhibits a much weaker pressure dependence than the direct bandgap, which is attributed to the emission process associated with highly localized states. Using the localized states emission as an energy reference, the deformation potential of the band edges of InN and In0.5Ga0.5N were determined.

  19. Aluminum-rich aluminum gallium nitride alloys and aluminum nitride epilayers

    NASA Astrophysics Data System (ADS)

    Nakarmi, Mim Lal

    Al-rich AlGaN alloys are ideal materials for the development of chip-scale optoelectronic devices such as deep ultraviolet (UV) emitters and detectors operating at wavelengths (lambda) down to 200 nm. Al-rich AlGaN and AlN epilayers were grown on sapphire substrates by metal organic chemical vapor deposition (MOCVD) for implementation in deep UV emitters. The materials were characterized by deep UV photoluminescence (PL), X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), and Hall-effect measurements. A method to grow high quality AlN epilayers was developed. AlN epilayers of optical quality as good as that of GaN have been achieved with surface roughness as low as 0.7 nm and full width at half maximum of XRD rocking at (0002) as low as 50 arcsec. Highly conductive n- and p-type Al-rich AlxGa1-x N alloys with Al content (x) as high as 0.7 are required in deep UV emitters (lambda < 300 nm). Si-and Mg-doped AI-rich AlGaN alloys were grown on AlN epilayer/sapphire templates. The correlation between the electrical properties and optical emission properties of Al-rich AlGaN alloys was studied. We found that the dominant band-edge emissions and suppressed impurity transitions related to intrinsic defects in PL lead to better conductivity in the materials. By controlling the compensating defects, undoped Al0.67Ga 0.33N epilayers grown on AIN epilayer/sapphire templates exhibit n-type conductivity with a resistivity of about 85 O cm at room temperature. Hall-effect and PL measurement show the existence of a shallow donor level with activation energy of about 90 meV. Electrical properties of highly conductive n-type AlxGa 1-xN (x ? 0.7) alloys have been studied. Si-doping concentration (NSi) dependence was studied for x = 0.7. We have achieved a record low n-type resistivity of 0.0075 O cm for NSi = 6 x 1019 cm-3. For x > 0.7, the resistivity was observed to increase by one order of magnitude as the Al content was increased by about 8%. The donor activation energy was systematically measured and varied from 10 meV to 180 meV as x increased from 0.7 to 1. Electrical and optical properties of Mg-doped Al0.7Ga 0.3N epilayers were studied. The activation energy of Mg acceptor is found to be around 400 meV. The optimized Mg-doped Al0.7Ga 0.3N epilayers have been incorporated into deep UV light emitting diode (LED) (lambda < 300 nm) structures as an electron blocking layer. An enhancement in the performance of the UV LEDs was obtained. Mg-delta-doping in AlGaN epilayers was investigated by MOCVD. From electrical, optical and structural studies, it has been demonstrated that Mg-delta-doping improves not only the p-type conduction, but also the overall quality of the epilayers.

  20. Gallium Safety in the Laboratory

    SciTech Connect

    Lee C. Cadwallader

    2003-06-01

    A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

  1. Gallium Safety in the Laboratory

    SciTech Connect

    Cadwallader, L.C.

    2003-05-07

    A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

  2. Development of gallium aluminum phosphide electroluminescent diodes

    NASA Technical Reports Server (NTRS)

    Chicotka, R. J.; Lorenz, M. R.; Nethercot, A. H.; Pettit, G. D.

    1972-01-01

    Work done on the development of gallium aluminum phosphide alloys for electroluminescent light sources is described. The preparation of this wide band gap semiconductor alloy, its physical properties (particularly the band structure, the electrical characteristics, and the light emitting properties) and work done on the fabrication of diode structures from these alloys are broadly covered.

  3. Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

    E-print Network

    Deseri, Luca

    Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium properties of liquid gallium and eutectic gallium-indium Phys. Fluids 24, 063101 (2012); 10); 10.1063/1.3670048 Evaluation of gallium-indium alloy as an acoustic couplant for high-impedance, high

  4. Gallium arsenide recycle chemistry and metallurgy

    SciTech Connect

    Bartlett, R.W.

    1987-03-23

    Research was successfully conducted on a smelting approach to separate gallium from arsenic using a liquid copper alloy to collect arsenic while oxidizing the gallium into a soda-silica slag. The slag and copper form two immiscible liquid phases. With GaAs in powder form, smelting at 1150 to 1220{degree}C yields 98% of the gallium in the slag and at least 96% of the arsenic in the copper. The gallium concentration in this slag is, relative to other sources, very high, and it can be processed further to obtain crude gallium. The effect of chemical oxidizers on arsenic and gallium distribution between slag and copper was determined. The solidified copper-arsenic alloy is environmentally inert. However, any precious metals present with the electronic scrap will nearly completely collect in the copper. Commercial copper refineries are capable of recovering precious metals from the copper-arsenic alloy, and are equipped to handle large amounts of arsenic when compared with the amount of arsenic used in GaAs devices, even with many fold future expansions.

  5. Bismuth in gallium arsenide: Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys

    SciTech Connect

    Reshak, Ali Hussain, E-mail: maalidph@yahoo.co.uk [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Kamarudin, H. [School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Auluck, S. [National Physical Laboratory Dr. KS Krishnan Marg, New Delhi 110012 (India); Kityk, I.V. [Electrical Engineering Department, Technological University of Czestochowa, Al. Armii Krajowej 17/19, Czestochowa (Poland)

    2012-02-15

    The structural and electronic properties of cubic GaAs{sub 1-x}Bi{sub x} alloys with bismuth concentration 0.0, 0.25, 0.50, 0.75 and 1.0 are studied using the 'special quasi-random structures' (SQS) approach of Zunger along with the generalized gradient approximation (GGA) and the Engel-Vosko generalized gradient approximation (EV-GGA). The lattice constant, bulk modulus, derivative of bulk modulus and energy gap vary with bismuth concentration nonlinearly. The present calculations show that the band gap decreases substantially with increasing bismuth concentration and that spin-orbit coupling influences the nature of bonding at high Bi concentrations. - Graphical abstract: Bowing effect of spin-orbit split-off band values versus Bi content with and without spin-orbit coupling for GaAs{sub 1-x}Bi{sub x} (at x=0.25, 0.50 and 0.75). Calculations are done with GGA. Highlights: Black-Right-Pointing-Pointer Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys were studied. Black-Right-Pointing-Pointer We present results of lattice constant, energy gap, bulk modulus and derivative. Black-Right-Pointing-Pointer The band gap decreases substantially with increasing Bi concentration. Black-Right-Pointing-Pointer Calculations of the density of states and charge densities are also presented. Black-Right-Pointing-Pointer We have performed calculations without and with spin-orbit coupling.

  6. Molecular-beam epitaxial growth and characterization of indium-gallium-nitride based alloys, heterostructures and multi-quantum wells

    NASA Astrophysics Data System (ADS)

    Singh, Rajminder

    Optical devices based on III-V nitrides operating in the visible region involve GaN as well as InGaN alloys. The development of such devices requires the optimization of both GaN and InGaN alloys. This thesis addresses issues related to the growth and characterization of InGaN alloys, both in the form of thick films as well as in the form of double heterostructures (Al)GaN/InGaN/(Al)GaN or multi-quantum wells. Methods have been developed to grow pure GaN thin films with excellent structural and optoelectronic properties. Such films have been intentionally doped with Si (n-type) and Mg (p-type). The room temperature carrier concentrations in the n-type films can be controlled from 10sp{16}-10sp{19}\\ cmsp{-3} with peak mobilities of 200 cmsp2/V-sec. The p-type Mg-doped films were found to have carrier concentrations up to 5× 10sp{17} cmsp{-3} without the need for any post-growth processing for the activation of Mg-acceptors. The relation between XRD measurements and dislocation densities measured by TEM in these high quality films has also been determined. InGaN bulk films were found to undergo phase separation of pure InN as detected by XRD when the indium concentration exceeds 35%. However, such phase separation was not observed when the same alloys were incorporated in film thickness less than 500 A. By employing indium in thin InGaN layers in the form of double heterostructures (DH), up to 81% of indium has been successfully incorporated. Calculations indicate that this phase separation is thermodynamically expected since the growth temperature is within the miscibility gap. The critical temperature of miscibility for this pseudo-binary system, based on the delta lattice parameter theory, is computed to be 2457 K. Multi-quantum wells of InGaN/AlGaN with thickness of about 100 A for the wells and barriers were fabricated. Upon optical pumping at room temperature, such structures were found to emit narrow luminescence with tunable wavelength in the visible region and quantum efficiency significantly higher than bulk InGaN. Sub-micron spatial resolution photoluminescence studies revealed that radiative recombination efficiency in InGaN quantum wells is 50-60 times that in bulk GaN. Single quantum well/double heterostructure and multi-quantum well InGaN/(Al)GaN LED structures have been fabricated and evaluated. Typical DH LEDs had a turn-on voltage of about 2V. Optical spectra were characteristic of emission in the InGaN layer with FWHM of about 50 nm at room temperature. Issues related to the processing of these LED devices have also been addressed.

  7. Gallium-cooled liquid metallic-fueled fast reactor

    Microsoft Academic Search

    T. Sawada; A. Netchaev; H. Ninokata; H. Endo

    2000-01-01

    We have examined the effects on core characteristics of using two different types of Pu-based metallic alloy fuels in the gallium-cooled fast reactor core. In the proposed concept, the liquid metal fast nuclear reactor uses metallic fuel in the liquid phase and gallium coolant at high temperature (inlet 1700K, outlet 1900K). The liquid fuel is continuously supplied to the reactor

  8. Investigations in gallium removal

    SciTech Connect

    Philip, C.V.; Pitt, W.W. [Texas A and M Univ., College Station, TX (United States); Beard, C.A. [Amarillo National Resource Center for Plutonium, TX (United States)

    1997-11-01

    Gallium present in weapons plutonium must be removed before it can be used for the production of mixed-oxide (MOX) nuclear reactor fuel. The main goal of the preliminary studies conducted at Texas A and M University was to assist in the development of a thermal process to remove gallium from a gallium oxide/plutonium oxide matrix. This effort is being conducted in close consultation with the Los Alamos National Laboratory (LANL) personnel involved in the development of this process for the US Department of Energy (DOE). Simple experiments were performed on gallium oxide, and cerium-oxide/gallium-oxide mixtures, heated to temperatures ranging from 700--900 C in a reducing environment, and a method for collecting the gallium vapors under these conditions was demonstrated.

  9. Magnetic field-induced phase transformation and variant reorientation in nickel-manganese-gallium and nickel-manganese-cobalt-indium magnetic shape memory alloys

    Microsoft Academic Search

    Haluk Ersin Karaca

    2007-01-01

    The purpose of this work is to reveal the governing mechanisms responsible for the magnetic field-induced (i) martensite reorientation in Ni 2MnGa single crystals, (ii) stress-assisted phase transformation in Ni2MnGa single crystals and (iii) phase transformation in NiMnCoIn alloys. The ultimate goal of utilizing these mechanisms is to increase the actuation stress levels in magnetic shape memory alloys (MSMAs). Extensive

  10. Bulk cubic gallium nitride

    SciTech Connect

    Purdy, A.P.

    1999-01-01

    Bulk cubic gallium nitride is made by charging into a reaction vessel to a fill of 25--95% having a temperature difference between its ends of at least 1 deg C a gallium precursor, sufficient amount of an acid mineralizer to form product zinc blende gallium nitride, and sufficient amount of ammonia to at least solubilize the precursor; sealing the reaction vessel; heating contents of the reaction vessel to at least 150 deg C while autogenously pressurizing contents of the reaction vessel to at least 500 psi for a duration sufficient to form the product zinc blende gallium nitride; cooling contents of the reaction vessel; and removing from the reaction vessel the product zinc blende gallium nitride.

  11. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  12. Aluminum battery alloys

    DOEpatents

    Thompson, David S. (Richmond, VA); Scott, Darwin H. (Mechanicsville, VA)

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  13. Visible light electroluminescent diodes of indium-gallium phosphide

    NASA Technical Reports Server (NTRS)

    Clough, R.; Richman, D.; Tietjen, J.

    1970-01-01

    Vapor deposition and acceptor impurity diffusion techniques are used to prepare indium-gallium phosphide junctions. Certain problems in preparation are overcome by altering gas flow conditions and by increasing the concentration of phosphine in the gas. A general formula is given for the alloy's composition.

  14. Energy-based quasi-static modeling of the actuation and sensing behavior of single-crystal iron-gallium alloys

    NASA Astrophysics Data System (ADS)

    Atulasima, Jayasimha; Flatau, Alison B.; Cullen, James R.

    2008-01-01

    An energy based model [W. D. Armstrong, J. Appl. Phys. 81, 2321 (1997); J. Atulasimha, Ph.D. thesis, Aerospace Engineering, University of Maryland, College Park, MD, 2006] is employed to predict the actuation (? -H and B -H at various compressive stresses) and sensing behavior (B -? and ? -? at various bias fields) of single-crystal FeGa alloys. The significant feature of this formulation is that, in addition to modeling actuation behavior, the sensing behavior can be predicted based on parameters estimated from the actuator characteristics. These predictions are then validated against experimental data for furnace cooled 19 at. % [100] oriented single-crystal FeGa alloys. Furthermore, an attempt is made to couple the energy-based sensing model with a lumped-parameter model that simulates the magnetic interaction between the magnetostrictive specimen and the magnetic circuit comprising the transducer. This enables a prediction of the variation in field through the sample due to changes in reluctance of the magnetostrictive sample with stress, as well as the impact of this variation in field on the B -? and ? -? curves. These predictions are benchmarked against experimental data, wherein the bias field varies due to change in sample reluctance with application of compressive stress while the drive current to the transducer is maintained constant.

  15. Metal Contacts to Gallium Arsenide.

    NASA Astrophysics Data System (ADS)

    Ren, Fan

    1991-07-01

    While various high performance devices fabricated from the gallium arsenide (GaAs) and related materials have generated considerable interest, metallization are fundamental components to all semiconductor devices and integrated circuits. The essential roles of metallization systems are providing the desired electrical paths between the active region of the semiconductor and the external circuits through the metal interconnections and contacts. In this work, in-situ clean of native oxide, high temperature n-type, low temperature n-type and low temperature p-type ohmic metal systems have been studied. Argon ion mill was used to remove the native oxide prior to metal deposition. For high temperature process n-type GaAs ohmic contacts, Tungsten (W) and Tungsten Silicide (WSi) were used with an epitaxial grown graded Indium Gallium Arsenide (InGaAs) layer (0.2 eV) on GaAs. In addition, refractory metals, Molybdenum (Mo), was incorporated in the Gold-Germanium (AuGe) based on n-type GaAs ohmic contacts to replace conventional silver as barrier to prevent the reaction between ohmic metal and chlorine based plasma as well as the ohmic metallization intermixing which degrades the device performance. Finally, Indium/Gold-Beryllium (In/Au-Be) alloy has been developed as an ohmic contact for p-type GaAs to reduce the contact resistance. The Fermi-level pinning of GaAs has been dominated by the surface states. The Schottky barrier height of metal contacts are about 0.8 V regardless of the metal systems. By using p-n junction approach, barrier height of pulsed C-doped layers was achieved as high as 1.4 V. Arsenic implantation into GaAs method was also used to enhance the barrier height of 1.6 V.

  16. Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium

    E-print Network

    Xu, Qin; Guo, Qiti; Jaeger, Heinrich; Brown, Eric

    2012-01-01

    Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-...

  17. Interaction of sodium with tellurium in gallium melts

    SciTech Connect

    Dergacheva, M.B.; Sarsekeeva, R.Zh.; Kozin, L.F.

    1988-09-20

    The purpose of this work was to study interaction of sodium with admixtures of tellurium and to determine the composition and phase state of the intermetallic compounds formed. The investigations were carried out by a potentiometric method with measurement of emf of the concentration cells. Sodium was introduced into the original gallium-tellurium binary alloy by electrolysis. The results of measurements of the emf of the cell were used for plotting potentiometric curves. The emf values found on the horizontal region of the potentiometric were subjected to mathematical analysis for determination of deviations from the regression line of the results of three parallel series of measurement. The emf of concentration cells with a solid electrolyte, based on melts of the gallium-sodium-tellurium ternary system, deviate from the theoretical values at 855 K; this is attributed to formation of the intermetallic compound, sparingly soluble in gallium, the free energy of formation of which is -266 +/- 15 kJ/mole.

  18. Polymorphism of Ga-In alloys in nanoconfinement conditions

    NASA Astrophysics Data System (ADS)

    Latysheva, E. N.; Pirozerskii, A. L.; Charnaya, E. V.; Kumzerov, Yu. A.; Fokin, A. V.; Nedbai, A. I.; Bugaev, A. S.

    2015-01-01

    The results of acoustic investigations of the melting and crystallization of indium-gallium alloys of different compositions embedded in porous glass matrices with a pore size of 18 nm are presented. It was shown that the formation of the ? and ? crystalline modifications of gallium is possible depending on the alloy composition in nanopores. The fraction of ?-Ga increased as the indium concentration in the alloy increased. Stabilization of ?-Ga in conditions of confined geometry was revealed. Broadening of the melting region of the ? phase of gallium and narrowing of the melting region of ?-Ga, as compared with the corresponding bulk alloys, were observed.

  19. Gallium interactions with Zircaloy

    SciTech Connect

    Woods, A.L. [ed.; West, M.K. [Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

    1999-01-01

    This study focuses on the effects of gallium ion implantation into zircaloy cladding material to investigate the effects that gallium may have in a reactor. High fluence ion implantation of Ga ions was conducted on heated Zircaloy-4 in the range of 10{sup 16}--10{sup 18} Ga ions/cm2. Surface effects were studied using SEM and electron microprobe analysis. The depth profile of Ga in the Zircaloy was characterized with Rutherford backscattering and SIMS techniques. Results indicate that the Zirc-4 is little affected up to a fluence of 10{sup 17} Ga ions/cm{sup 2}. After implantation of 10{sup 18} Ga ions/cm{sup 2}, sub-grain features on the order of 2 {micro}m were observed which may be due to intermetallic compound formation between Ga and Zr. For the highest fluence implant, Ga content in the Zirc-4 reached a saturation value of between 30 and 40 atomic %; significant enhanced diffusion was observed but gallium was not seen to concentrate at grain boundaries.

  20. Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing

    NASA Astrophysics Data System (ADS)

    Alur, Siddharth

    Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

  1. Sputtering of tin and gallium-tin clusters

    SciTech Connect

    Lill, T.; Calaway, W.F.; Ma, Z.; Pellin, M.J.

    1994-08-01

    Tin and gallium-tin clusters have been produced by 4 keV Ar{sup +} ion bombardment of polycrystalline tin and the gallium-tin eutectic alloy and analyzed by time-of-flight mass spectrometry. The sputtered neutral species were photoionized with 193 nm (6.4 eV) excimer laser light. Neutral tin clusters containing up to 10 atoms and mixed gallium-tin clusters Ga{sub (n-m)}Sn{sub m} with n {<=} 4 for the neutrals and N {<=} 3 for the sputtered ionic species have been detected. Laser power density dependent intensity measurements, relative yields, and kinetic energy distributions have been measured. The abundance distributions of the mixed clusters have been found to be nonstatistical due to significant differences in the ionization efficiencies for clusters with equal nuclearity but different number of tin atoms. The results indicate that Ga{sub 2}Sn and Ga{sub 3}Sn like the all-gallium clusters have ionization potentials below 6.4 eV. In the case of Sn{sub 5}, Sn{sub 6}, GaSn and Ga{sub (n-m)}Sn{sub m} clusters with n=2 to 4 and m>1, the authors detect species that have sufficient internal energy to be one photon ionized despite ionization potentials that are higher 6.4 eV. The tin atom signal that is detected can be attributed to photofragmentation of dimers for both sputtering from polycrystalline tin and from the gallium-tin eutectic alloy.

  2. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

    1996-01-01

    Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

  3. Alloys

    NASA Astrophysics Data System (ADS)

    Jung, Sung-Jin; Kim, Seong Keun; Park, Hyung-Ho; Hyun, Dow-Bin; Baek, Seung-Hyub; Kim, Jin-Sang

    2014-06-01

    The effects of mechanical deformation and subsequent annealing on the thermoelectric properties and microstructure have been investigated for p-type (Bi0.25Sb0.75)2Te3 alloys prepared by melting followed by quenching. The mechanically deformed pellets were prepared by repetition of cold-pressing of quenched samples at room temperature. Cold-pressed pellets were then annealed at 300°C in vacuum, and the thermoelectric properties and microstructure were traced through the course of the heat treatment. For the heavily deformed samples, the Seebeck coefficient rapidly increased at the very early stage of annealing and did not change as the annealing time increased, due to recrystallization of a new ?-phase which equilibrated at the annealing temperature of 300°C (?300-phase). At the initial stage of annealing (recovery stage), the electrical resistivity sharply increased, probably due to the interaction of antistructural defects with vacancies produced during the cold-pressing treatment. However, for the lightly deformed samples, recrystallization occurred only at some portion of the grain boundaries, and the newly generated ?300-phase slowly replaced the original, as-solidified ?ingot-phase.

  4. Electrospun Gallium Nitride Nanofibers

    SciTech Connect

    Melendez, Anamaris; Morales, Kristle; Ramos, Idalia [University of Puerto Rico at Humacao, Humacao (Puerto Rico); Campo, Eva [Centre Nacional de Microelectronica, Barcelona (Spain); Santiago, Jorge J. [University of Pennsylvania, Philadelphia (United States)

    2009-04-19

    The high thermal conductivity and wide bandgap of gallium nitride (GaN) are desirable characteristics in optoelectronics and sensing applications. In comparison to thin films and powders, in the nanofiber morphology the sensitivity of GaN is expected to increase as the exposed area (proportional to the length) increases. In this work we present electrospinning as a novel technique in the fabrication of GaN nanofibers. Electrospinning, invented in the 1930s, is a simple, inexpensive, and rapid technique to produce microscopically long ultrafine fibers. GaN nanofibers are produced using gallium nitrate and dimethyl-acetamide as precursors. After electrospinning, thermal decomposition under an inert atmosphere is used to pyrolyze the polymer. To complete the preparation, the nanofibers are sintered in a tube furnace under a NH{sub 3} flow. Both scanning electron microscopy and profilometry show that the process produces continuous and uniform fibers with diameters ranging from 20 to a few hundred nanometers, and lengths of up to a few centimeters. X-ray diffraction (XRD) analysis shows the development of GaN nanofibers with hexagonal wurtzite structure. Future work includes additional characterization using transmission electron microscopy and XRD to understand the role of precursors and nitridation in nanofiber synthesis, and the use of single nanofibers for the construction of optical and gas sensing devices.

  5. Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium

    E-print Network

    Qin Xu; Nikolai Qudalov; Qiti Guo; Heinrich Jaeger; Eric Brown

    2012-01-23

    Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-like to liquid behavior at the same critical acid concentration, thereby quantitatively confirming that the wettability of these liquid metals is due to the oxide skin.

  6. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  7. Renal amyloidosis. Evaluation by gallium imaging

    SciTech Connect

    Lee, V.W.; Skinner, M.; Cohen, A.S.; Ngai, S.; Peng, T.T.

    1986-09-01

    A study has been performed to evaluate the efficacy of gallium imaging in the detection of renal amyloidosis. Ten of the 11 patients who had biopsy-proven renal amyloidosis demonstrated marked uptake in both kidneys. One patient revealed moderate gallium uptake in his kidneys. None of the patients had underlying renal or extrarenal pathology other than amyloidosis, which could account for renal gallium uptake (renal infection, neoplasm, hepatic failure or frequent blood transfusions). Four patients also had extrarenal foci of abnormal gallium uptake, suggesting other sites of amyloid deposits. Our data strongly suggest that gallium imaging has a high sensitivity for detection of renal amyloidosis. Its specificity is enhanced significantly by careful review of the clinical history to exclude other known causes of renal gallium uptake. Potentially, gallium imaging may be used to monitor the progress of patients under experimental therapy.

  8. P-type gallium nitride

    DOEpatents

    Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

    1997-08-12

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

  9. Gallium scintigraphy in acute panniculitis

    SciTech Connect

    Choy, D. (Prince of Wales Hospital, Randwick, Australia); Murray, I.P.C.; Ford, J.C.

    1981-11-01

    Gallium scintigraphy was performed in a 27-yr-old female in search of a possible occult focus of infection; it showed an unusual diffuse superficial accumulation in the thighs and buttocks. Biopsy of an area of abnormal uptake showed lobular panniculitis which, in the clinical context, led to the diagnosis of Weber-Christian syndrome.

  10. P-type gallium nitride

    DOEpatents

    Rubin, Michael (Berkeley, CA); Newman, Nathan (Montara, CA); Fu, Tracy (Berkeley, CA); Ross, Jennifer (Pleasanton, CA); Chan, James (Berkeley, CA)

    1997-01-01

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5.times.10.sup.11 /cm.sup.3 and hole mobilities of about 500 cm.sup.2 /V-sec, measured at 250.degree. K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al.

  11. Gallium nitride electronics

    NASA Astrophysics Data System (ADS)

    Rajan, Siddharth; Jena, Debdeep

    2013-07-01

    In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it an excellent reference for newcomers and experienced researchers in this field for several years. We thank Alice Malhador at IOP Publishing for her constant encouragement and guidance in putting together this special issue on GaN electronics.

  12. Study of the Local Structure of GALLIUM(X)INDIUM(1 -X)ARSENIDE(Y)ANTIMONY(1-Y), a Quaternary Iii-V Semiconductor Alloy, Using the Extended X-Ray Absorption Fine Structure (exafs) Technique.

    NASA Astrophysics Data System (ADS)

    Islam, Shaheen Momtaz

    The technological importance of quaternary semiconductor alloys has stimulated considerable interest in the basic physics of these materials. Understanding of the local structure of these alloys is of fundamental importance. In this work, the extended x-ray absorption fine structure (EXAFS) technique has been used to investigate the atomic-scale structure of the III-V quaternary alloy series Ga_{rm x}In _{rm 1-x}As _{rm y}Sb_ {rm 1-y}, where Ga and In atoms occupy one sublattice and As and Sb atoms are distributed over the other sublattice. Two series of these alloys were studied with varying x (from 0.05 to 0.95) and keeping y constant (y = 0.05 or y = 0.10). The samples were polycrystalline powders of various compositions. EXAFS data were obtained at the As K-edge at room temperature for all these alloys. Our measurements reveal the number and types of atoms and the nearest neighbor distances about the average As atom. Our results show a consistent deviation from random site occupation in all these alloys, with Ga-As (and therefore In-Sb) pairs being clearly preferred over In-As and Ga -Sb pairs. This result is consistent with a theoretical model based on the pair approximation. From EXAFS measurements we also observe that the variation of Ga-As and In-As near-neighbor distances with composition is linear and that the bond-lengths remain nearly constant, closer to those in the pure binary compounds and varying only by 0.03 to 0.05A. On the other hand, the x-ray diffraction results show that the average cation -anion distance in the alloys changes by as much as 0.165A in accordance with Vegard's law. This linear variation of lattice constant with composition between the end members suggests that the atomic volume is conserved regardless of the details of the local distortions of lattice.

  13. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Copper gallium indium selenide. 721.10391 Section 721...Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance...substance identified as copper gallium indium selenide (PMN P-10-424; CAS...

  14. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Copper gallium indium selenide. 721.10391 Section 721...Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance...substance identified as copper gallium indium selenide (PMN P-10-424; CAS...

  15. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Copper gallium indium selenide. 721.10391 Section 721...Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance...substance identified as copper gallium indium selenide (PMN P-10-424; CAS...

  16. Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system

    E-print Network

    Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system Kangkang, University of Michigan, Ann Arbor, MI 48109, U.S.A. ABSTRACT Ferromagnetic delta-phase manganese gallium to their potential for novel spintronics applications such as spin light-emitting diodes[1] . Delta phase manganese

  17. Gallium poisoning: A rare case report

    Microsoft Academic Search

    Chris S. Ivanoff; Athena E. Ivanoff; Timothy L. Hottel

    The authors present a case of a college student who suffered acute gallium poisoning as a result of accidental exposure to gallium halide complexes. This is extremely rare and has never been reported in the literature. Acute symptoms after the incident, which initially presented as dermatitis and appeared relatively not life-threatening, rapidly progressed to dangerous episodes of tachycardia, tremors, dyspnea,

  18. Processing to obtain high-purity gallium

    NASA Astrophysics Data System (ADS)

    Bautista, Renato G.

    2003-03-01

    Gallium has become increasingly popular as a substrate material for electronic devices. Aside from ore, gallium can be obtained from such industrial sources as the Bayer process caustic liquor that is a byproduct of bauxite processing, flue dust removed from the fume-collection system in plants that produce aluminum by the electrolytic process, zinc refinery residues, gallium scrap materials, and coal fly ash. The purification process for gallium can start with solvent-extraction processes where the concentrations of impurities, especially metals, are reduced to the ppm range. This article describes how ultra-purification techniques can be employed to reduce the undesirable impurities to the low ppb range. The various procedures described give an idea as to the extent of work needed to obtain and prepare high-purity gallium for electronic application.

  19. Gallium Electromagnetic (GEM) Thrustor Concept and Design

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.

    2006-01-01

    We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

  20. The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal

    SciTech Connect

    Richmond, Scott [Los Alamos National Laboratory; Bridgewater, Jon S [Los Alamos National Laboratory; Ward, John W [Los Alamos National Laboratory; Allen, Thomas A [Los Alamos National Laboratory

    2009-01-01

    Pressure-Composition-Temperature (PCT) data are presented for the plutonium-hydrogen (Pu-H) and plutonium-deuterium (Pu-D) systems in the solubility region up to terminal solubility (precipitation of PuH{sub 2}). The heats of solution for PuH{sub s} and PuD{sub s} are determined from PCT data in the ranges 350-625 C for gallium alloyed Pu and 400-575 C for unalloyed Pu. The solubility of high purity plutonium alloyed with 2 at.% gallium is compared to high purity unalloyed plutonium. Significant differences are found in hydrogen solubility for unalloyed Pu versus gallium alloyed Pu. Differences in hydrogen solubility due to an apparent phase change are observable in the alloyed and unalloyed solubilities. The effect of iron impurities on Pu-Ga alloyed Pu is shown via hydrogen solubility data as preventing complete homogenization.

  1. The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal

    NASA Astrophysics Data System (ADS)

    Richmond, S.; Bridgewater, J. S.; Ward, J. W.; Allen, T. H.

    2010-03-01

    Pressure-Composition-Temperature (PCT) data are presented for the plutonium-hydrogen (Pu-H) and plutonium-deuterium (Pu-D) systems in the solubility region up to terminal solubility (precipitation of PuH2). The heats of solution for PuHS and PuDS are determined from PCT data in the ranges 350-625°C for gallium alloyed Pu and 400-575°C for unalloyed Pu. The solubility of high purity plutonium alloyed with 2 at.% gallium is compared to high purity unalloyed plutonium. Significant differences are found in hydrogen solubility for unalloyed Pu versus gallium alloyed Pu. Differences in hydrogen solubility due to an apparent phase change are observable in the alloyed and unalloyed solubilities. The effect of iron impurities on Pu-Ga alloyed Pu is shown via hydrogen solubility data as preventing complete homogenization.

  2. Clinical Applications of Gallium-68

    PubMed Central

    Banerjee, Sangeeta Ray; Pomper, Martin G.

    2013-01-01

    Gallium-68 is a positron-emitting radioisotope that is produced from a 68Ge/68Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. 68Ga-DOTATOC, 8Ga-DOTATATE, 68Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with 68Ga over the past few years around the world, including within the United States. An estimated ~10,000 scans are being performed yearly in Europe at about 100 centers utilizing 68Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied 68Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

  3. In vitro bio-functionality of gallium nitride sensors for radiation biophysics

    SciTech Connect

    Hofstetter, Markus [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Howgate, John [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Schmid, Martin [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Schoell, Sebastian; Sachsenhauser, Matthias [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Adiguezel, Denis [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Stutzmann, Martin; Sharp, Ian D. [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Thalhammer, Stefan, E-mail: stefan.thalhammer@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

    2012-07-27

    Highlights: Black-Right-Pointing-Pointer Gallium nitride based sensors show promising characteristics to monitor cellular parameters. Black-Right-Pointing-Pointer Cell growth experiments reveal excellent biocompatibiltiy of the host GaN material. Black-Right-Pointing-Pointer We present a biofunctionality assay using ionizing radiation. Black-Right-Pointing-Pointer DNA repair is utilized to evaluate material induced alterations in the cellular behavior. Black-Right-Pointing-Pointer GaN shows no bio-functional influence on the cellular environment. -- Abstract: There is an increasing interest in the integration of hybrid bio-semiconductor systems for the non-invasive evaluation of physiological parameters. High quality gallium nitride and its alloys show promising characteristics to monitor cellular parameters. Nevertheless, such applications not only request appropriate sensing capabilities but also the biocompatibility and especially the biofunctionality of materials. Here we show extensive biocompatibility studies of gallium nitride and, for the first time, a biofunctionality assay using ionizing radiation. Analytical sensor devices are used in medical settings, as well as for cell- and tissue engineering. Within these fields, semiconductor devices have increasingly been applied for online biosensing on a cellular and tissue level. Integration of advanced materials such as gallium nitride into these systems has the potential to increase the range of applicability for a multitude of test devices and greatly enhance sensitivity and functionality. However, for such applications it is necessary to optimize cell-surface interactions and to verify the biocompatibility of the semiconductor. In this work, we present studies of mouse fibroblast cell activity grown on gallium nitride surfaces after applying external noxa. Cell-semiconductor hybrids were irradiated with X-rays at air kerma doses up to 250 mGy and the DNA repair dynamics, cell proliferation, and cell growth dynamics of adherent cells were compared to control samples. The impact of ionizing radiation on DNA, along with the associated cellular repair mechanisms, is well characterized and serves as a reference tool for evaluation of substrate effects. The results indicate that gallium nitride does not require specific surface treatments to ensure biocompatibility and suggest that cell signaling is not affected by micro-environmental alterations arising from gallium nitride-cell interactions. The observation that gallium nitride provides no bio-functional influence on the cellular environment confirms that this material is well suited for future biosensing applications without the need for additional chemical surface modification.

  4. Status of gallium-67 in tumor detector

    SciTech Connect

    Hoffer, P.

    1980-04-01

    The efficacy of gallium-67 citrate in detecting specific tumors is discussed. Tumors in which gallium-67 imaging is useful as a diagnostic tool include Hodgkin's disease, histiocystic lymphoma, Burkitt's lymphoma, hepatoma melanoma, and leukemia. It has not been found to be effective in diagnosing head and neck tumors, gastrointestinal tumors, genitourinary tract tumors, breast tumors, and pediatric tumors. Gallium may be useful in the evaluation of non-Hodgkin's lymphoma, testicular carcinoma, mesothelioma, and carcinoma of the lung. It may also be useful for determining response to treatment and prognosis in some neoplasms.

  5. Recovery of gallium from aluminum industry residues

    SciTech Connect

    Carvalho, M.S.; Neto, K.C.M.; Nobrega, A.W.; Medeiros, J.A.

    2000-01-01

    A procedure is proposed to recover gallium from flue dust aluminum residues produced in plants by using solid-phase extraction with a commercial polyether-type polyurethane foam (PUF). Gallium can be separated from high concentrations of aluminum, iron, nickel, titanium, vanadium, copper, zinc, sulfate, fluoride, and chloride by extraction with PUF from 3 M sulfuric acid and 3 M sodium chloride concentration medium with at least a 92% efficiency. Gallium backextraction was fast and quantitative with ethanol solution. In all recovery steps commercial-grade reagents could be used, including tap water. The recovered gallium was precipitated with sodium hydroxide solution, purified by dissolution and precipitation, calcinated, and the final oxide was 98.6% pure.

  6. 49 CFR 173.162 - Gallium.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Regulations Relating to Transportation PIPELINE AND HAZARDOUS...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...performance level for transportation by aircraft, and...transport gallium at low temperatures in...permit the release of carbon dioxide gas....

  7. 49 CFR 173.162 - Gallium.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Regulations Relating to Transportation PIPELINE AND HAZARDOUS...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...performance level for transportation by aircraft, and...transport gallium at low temperatures in...permit the release of carbon dioxide gas....

  8. 49 CFR 173.162 - Gallium.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Regulations Relating to Transportation PIPELINE AND HAZARDOUS...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...performance level for transportation by aircraft, and...transport gallium at low temperatures in...permit the release of carbon dioxide gas....

  9. Gallium arsenide passivation through nitridation with hydrazine

    NASA Astrophysics Data System (ADS)

    Vogt, Kirkland W.; Kohl, Paul A.

    1993-11-01

    Passivating films were grown on gallium arsenide by direct nitridation with hydrazine at 300-400 °C. Auger electron spectroscopy and x-ray photoelectron spectroscopy analysis show that the films are primarily gallium nitride with an oxide impurity. The oxide content is a function of the surface pretreatment, reaction temperature, and water concentration in the hydrazine. Improvements in the band gap photoluminescence with nitridation indicate a lower surface state density and reflect an improvement in the termination of the semiconductor lattice.

  10. Gallium Arsenide wafer scale integration

    NASA Astrophysics Data System (ADS)

    McDonald, J. F.; Taylor, G.; Steinvorth, R.; Donlan, B.; Bergendahl, A. S.

    1985-08-01

    Gallium Arsenide (GaAs) digital MESFET technology has recently begun to appear in the semiconductor marketplace. The initial commercial offerings are at the small to medium scale integration levels. The high speed of these parts would seem to be very attractive for designers of high performance signal processing equipment. Persistent yield problems, however, have prevented the appearance of large scale integrated circuits. As a result, intrapackage and interpackage signal propagation problems such as coupling, parasitics and delay are likely to negate much of the benefits of the fast MESFET logic devices for large systems constructed with such small scale building blocks. An early packaging concept, Wafer Scale Integration (WSI), which could possibly be used to address some of these limitations is reexamined.

  11. Generator for gallium-68 and compositions obtained therefrom

    DOEpatents

    Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

    1981-01-01

    A generator for obtaining radioactive gallium-68 from germanium-68 bound in a resin containing unsubstituted phenolic hydroxyl groups. The germanium-68 is loaded into the resin from an aqueous solution of the germanium-68. A physiologically acceptable solution of gallium-68 having an activity of 0.1 to 50 millicuries per milliliter of gallium-68 solution is obtained. The solution is obtained from the bound germanium-68 which forms gallium-68 in situ by eluting the column with a hydrochloric acid solution to form an acidic solution of gallium-68. The acidic solution of gallium-68 can be neutralized.

  12. Palladium alloys for biomedical devices.

    PubMed

    Wataha, John C; Shor, Kavita

    2010-07-01

    In the biomedical field, palladium has primarily been used as a component of alloys for dental prostheses. However, recent research has shown the utility of palladium alloys for devices such as vascular stents that do not distort magnetic resonance images. Dental palladium alloys may contain minor or major percentages of palladium. As a minor constituent, palladium hardens, strengthens and increases the melting range of alloys. Alloys that contain palladium as the major component also contain copper, gallium and sometimes tin to produce strong alloys with high stiffness and relatively low corrosion rates. All current evidence suggests that palladium alloys are safe, despite fears about harmful effects of low-level corrosion products during biomedical use. Recent evidence suggests that palladium poses fewer biological risks than other elements, such as nickel or silver. Hypersensitivity to palladium alone is rare, but accompanies nickel hypersensitivity 90-100% of the time. The unstable price of palladium continues to influence the use of palladium alloys in biomedicine. PMID:20583886

  13. Investigation of the thermal properties of gallium nitride using the three omega technique

    NASA Astrophysics Data System (ADS)

    Mion, Christian

    Gallium nitride based devices suffer from undesirable heating effects that significantly limit the performance of high electron mobility transistors and laser diodes thereby reducing device lifetime and reliability. An accurate knowledge of the gallium nitride thermal conductivity is crucial to understanding thermal effects. This work addresses issues related to both the thermal limitations and thermal characterization of gallium nitride alloys and devices. First, theoretical developments concerning the three omega technique applied to a film-on-substrate system are considered when the film-to-substrate thermal conductivity ratio is larger than one. The case of thermal boundary resistance between film and substrate is included. In the case of high thermal conductivity films, it is found that neglecting the presence of thin thermally insulating buffer layer would lead to large uncertainties in extracted film thermal conductivities. Next, very thick, free standing gallium nitride layers grown by hydride vapor phase epitaxy were precisely measured from 300K to 450K using the three omega method. By comparing the measured values with dislocation density measurements the dependence of the gallium nitride thermal conductivity on dislocation density was obtained and compared with theory. In addition, the thermal conductivity of iron doped semi-insulating gallium nitride was measured to be as high as 230 W·K-1·m-1. In this study, a 2mm thick iron doped gallium nitride substrate was measured to have an average dislocation density of 5.104 cm-2 which represents the present state of the art. Finally the modeling of the thermal resistance of multifinger AlGaN/GaN HEMTs was examined using the experimentally determined values of the thermal conductivity. Using the three omega method as the starting point, an original accurate closed-form compact expression for the thermal resistance of single and multifinger HEMT device structures was derived. It was found that the thermal performance of a single finger HEMT composed of homoepitaxial GaN on a GaN substrate is superior to that of single finger GaN HEMT heteroepitaxially grown on silicon carbide.

  14. Window structure for passivating solar cells based on gallium arsenide

    NASA Technical Reports Server (NTRS)

    Barnett, Allen M. (Inventor)

    1985-01-01

    Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

  15. GALLIUM--2001 29.1 By Deborah A. Kramer

    E-print Network

    capacity expansions, very few additional expansions were announced in 2001. Because gallium nitride (GaN-emitting diodes (LEDs)] as the second largest end use. World production of virgin gallium was estimated to be 81

  16. Proportional counter response calculations for gallium solar neutrino detectors

    Microsoft Academic Search

    R. T. Kouzes; D. Reynolds

    1989-01-01

    Gallium-based solar neutrino detectors are sensitive to the primary pp reaction in the sun. Two experiments using gallium, SAGE in the Soviet Union and GALLEX in Europe, are under construction and are scheduled to produce data by 1989. The radioactive 71Ge produced by neutrinos interacting with the gallium detector material is chemically extracted and counted in miniature proportional counters. A

  17. Atomistic modeling of thermodynamic properties of Pu-Ga alloys based on the Invar mechanism

    NASA Astrophysics Data System (ADS)

    Lee, Tongsik; Taylor, Christopher D.; Lawson, A. C.; Conradson, Steven D.; Chen, Shao Ping; Caro, A.; Valone, Steven M.; Baskes, Michael I.

    2014-05-01

    We present an atomistic model that accounts for a range of anomalous thermodynamic properties of the fcc ? phase of Pu-Ga alloys in terms of the Invar mechanism. Two modified embedded atom method potentials are employed to represent competing electronic states in ?-Pu, each of which has an individual configuration dependence as well as distinct interactions with gallium. Using classical Monte Carlo simulations, we compute the temperature dependence of various thermodynamic properties for different dilute gallium concentrations. The model reproduces the observed effects of excessive volume reduction along with a rapid shift in thermal expansion from negative to positive values with increasing gallium concentration. It also predicts progressive stiffening upon dilute-gallium alloying, while the calculated thermal softening is nearly independent of the gallium concentration in agreement with resonant ultrasound spectroscopy measurements in the literature. Analysis of the local structure predicted by the model indicates that the distribution of the gallium atoms is not completely random in the ? phase due to the presence of short-range order associated with the Invar mechanism. This effect is consistent with the nanoscale heterogeneity in local gallium concentration which is observed in recent extended x-ray absorption fine structure spectroscopy experiments. Implications of the Invar effect for phase stability and physical interpretations of the two states are also discussed.

  18. Gallium uptake in myositis ossificans. Potential pitfalls in diagnosis

    SciTech Connect

    Salzman, L.; Lee, V.W.; Grant, P.

    1987-04-01

    Seven cases of gallium uptake in myositis ossificans are described. Gallium scans are done frequently in paraplegics, quadriplegics, and comatose patients to look for occult infection. It is important to be aware of possible gallium uptake in myositis ossificans, particularly in the extremities, which is frequent in these patients. Gallium uptake may be present prior to any abnormalities seen on plain films or CT scans. It is important to correlate roentgenograms with abnormal gallium scans, particularly in the extremities, to avoid potential pitfalls in diagnosis and prevent unnecessary antibiotic treatment. A bone scan should be obtained whenever possible, particularly when roentgenograms are negative, to confirm the diagnosis.

  19. /sup 67/Gallium lung scans in progressive systemic sclerosis

    SciTech Connect

    Baron, M.; Feiglin, D.; Hyland, R.; Urowitz, M.B.; Shiff, B.

    1983-08-01

    /sup 67/Gallium lung scans were performed in 19 patients with progressive systemic sclerosis (scleroderma). Results were expressed quantitatively as the /sup 67/Gallium Uptake Index. The mean total pulmonary /sup 67/Gallium Uptake Index in patients was significantly higher than that in controls (41 versus 25), and 4 patients (21%) fell outside the normal range. There were no clinical or laboratory variables that correlated with the /sup 56/Gallium uptake. Increased pulmonary /sup 67/Gallium uptake in scleroderma may prove useful as an index of pulmonary disease activity.

  20. Four Terminal Gallium Nitride MOSFETs

    NASA Astrophysics Data System (ADS)

    Veety, Matthew Thomas

    All reported gallium nitride (GaN) transistors to date have been three-terminal devices with source, drain, and gate electrodes. In the case of GaN MOSFETs, this leaves the bulk of the device at a floating potential which can impact device threshold voltage. In more traditional silicon-based MOSFET fabrication a bulk contact can be made on the back side of the silicon wafer. For GaN grown on sapphire substrates, however, this is not possible and an alternate, front-side bulk contact must be investigated. GaN is a III-V, wide band gap semiconductor that as promising material parameters for use in high frequency and high power applications. Possible applications are in the 1 to 10 GHz frequency band and power inverters for next generation grid solid state transformers and inverters. GaN has seen significant academic and commercial research for use in Heterojunction Field Effect Transistors (HFETs). These devices however are depletion-mode, meaning the device is considered "on" at zero gate bias. A MOSFET structure allows for enhancement mode operation, which is normally off. This mode is preferrable in high power applications as the device has lower off-state power consumption and is easier to implement in circuits. Proper surface passivation of seminconductor surface interface states is an important processing step for any device. Preliminary research on surface treatments using GaN wet etches and depletion-mode GaN devices utilizing this process are discussed. Devices pretreated with potassium pursulfate prior to gate dielectric deposition show significant device improvements. This process can be applied to any current GaN FET. Enhancement-mode GaN MOSFETs were fabricated on magnesium doped p-type Wurtzite gallium nitride grown by Metal Organic Chemical Vapor Deposition (MOCVD) on c-plane sapphire substrates. Devices utilized ion implant source and drain which was activated under NH3 overpressure in MOCVD. Also, devices were fabricated with a SiO2 gate dielectric and metal gate. Preliminary devices exhibited high GaN-oxide interface state density, Dit, on the order of 1013 cm-2· eV-1. Additional experiments and device fabrication was focused on improving device performance through optimization of the ion implantation activation anneal as well as incorporation of a bulk p-type ohmic contact and migration to a thicker, lower defect density, HVPE-grown template substrate. The first reported MOSFET on HVPE grown GaN substrates (templates) is reported with peak measured drain current of 1.05 mA/mm and a normalized transconductance of 57 muS/mm. Fabricated devices exhibited large (greater than 1 muA) source-to-drain junction leakage which is attributed to low activated doping density in the MOCVD-grown p-type bulk. MOSFETs fabricated on template substrates show more than twice the measured drain current as similar devices fabricated on traditional MOCVD GaN on sapphire substrates for the same bias conditions. Also, template MOSFETs have decreased gate leakage which allowed for a much greater range of operation. This performance increase is attributed to a more than doubled effective channel mobility on template GaN MOSFETs due to decreased crystal defect scattering when compared to a MOCVD-grown GaN-on-sapphire MOSFET. Fabricated MOSFETs also exhibit decreased interface state density with lower bound of 2.2x1011 cm-2·eV-1 when compared to prelimary MOSFETs. This decrease is associated with the use of a sacrificial oxide cap during source/drain activation. Suggested work for continued research is also presented which includes experiments to improve source/drain ion implantation profile, utilization of selective area growth for the active area, improved n- and p-type ohmic contact resistance and investigation of alternate oxides.

  1. On the formation of surface gallium hydride species in supported gallium catalysts

    NASA Astrophysics Data System (ADS)

    Serykh, Alexander I.

    2012-10-01

    Molecular hydrogen is dissociatively adsorbed at elevated temperatures on Ga3+ surface sites of supported gallium catalysts. Both the amount of hydrogen absorbed by the catalysts and Gasbnd H vibration frequencies of surface gallium hydrides formed upon dissociative hydrogen adsorption depend on the nature of the support. The surface sites, active in the dissociative adsorption of hydrogen, most probably are Ga3+ cations bonded to the support surface.

  2. Synchrotron X-Ray Fluorescence Microscopy of Gallium in Bladder Tissue following Gallium Maltolate Administration during Urinary Tract Infection

    PubMed Central

    Sampieri, Francesca; Chirino, Manuel; Hamilton, Don L.; Blyth, Robert I. R.; Sham, Tsun-Kong; Dowling, Patricia M.; Thompson, Julie

    2013-01-01

    A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 ?g/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli. PMID:23877680

  3. High Pressure Solution Growth of Gallium Nitride

    NASA Astrophysics Data System (ADS)

    Bo?kowski, Michal; Str?k, Pawel; Grzegory, Izabella; Porowski, Sylwester

    State-of-the-art high pressure solution (HPS) growth of gallium nitride is presented in this chapter. The spontaneous crystallization and seeded growth are described in detail from the technological point of view. Two classes of pressure-grown crystals and their use as substrates for blue laser diodes (LDs) are demonstrated.

  4. Thermodynamic binding constants for gallium transferrin

    SciTech Connect

    Harris, W.R.; Pecoraro, V.L.

    1983-01-18

    Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga/sup 3 +/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants. Therefore, thermodynamic binding constants for gallium complexation at the two specific metal binding sites of human serum transferrin at pH 7.4 and 5 mM NaHCO/sub 3/ have been determined by UV difference spectroscopy. The conditional constants calculated for 27 mM NaHCO/sub 3/ are log K/sub 1/* = 20.3 and log K/sub 2/* = 19.3. These results are discussed in relation to the thermodynamics of transferrin binding of Fe/sup 3 +/ and to previous reports on gallium binding. The strength of transferrin complexation is also compared to that of a series of low molecular weight ligands by using calculated pM values (pM = -log (Ga(H/sub 2/O)/sub 6/)) to express the effective binding strength at pH 7.4.

  5. Extrapulmonary localization of gallium in sarcoidosis

    SciTech Connect

    Rohatgi, P.K.; Singh, R.; Vieras, F.

    1987-01-01

    This paper describes the spectrum of extrapulmonary localization of gallium in patients with sarcoidosis. The usefulness of Ga-67 scintiscans in detecting clinically occult lesions, in directing clinicians to accessible sites for biopsy, and in following the course of extrapulmonary sites of involvement with therapy is emphasized.

  6. A Gallium Multiphase Equation of State

    NASA Astrophysics Data System (ADS)

    Crockett, Scott; Greeff, Carl

    2009-06-01

    A new SESAME multiphase gallium equation of state (EOS) has been developed. The equation of state includes two of the solid phases (Ga I, Ga III) and a fluid phase. The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We will also explore refreezing via isentropic release and compression.

  7. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C. (Albuquerque, NM); Shul, Randy J. (Albuquerque, NM)

    1999-01-01

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  8. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, J.C.; Shul, R.J.

    1999-02-02

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  9. Gallium-positive Lyme disease myocarditis

    SciTech Connect

    Alpert, L.I.; Welch, P.; Fisher, N.

    1985-09-01

    In the course of a work-up for fever of unknown origin associated with intermittent arrhythmias, a gallium scan was performed which revealed diffuse myocardial uptake. The diagnosis of Lyme disease myocarditis subsequently was confirmed by serologic titers. One month following recovery from the acute illness, the abnormal myocardial uptake completely resolved.

  10. Gallium Electromagnetic (GEM) Thruster Performance Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

    2009-01-01

    Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

  11. Anisotropy of the magnetic susceptibility of gallium

    USGS Publications Warehouse

    Pankey, T., Jr.

    1960-01-01

    The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25??C. The following anisotropic diamagnetic susceptibilities were found: a axis (-0.119??0. 001)??10-6 emu/g, b axis (-0.416??0.002)??10 -6 emu/g, and c axis (-0.229??0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (-0.257??0.003)??10-6 emu/g at 25??C, and (-0.299??0.003)??10-6 emu/g at -196??C. The susceptibility of liquid gallium was (0.0031??0.001) ??10-6 emu/g at 30??C and 100??C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi-energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state. ?? 1960 The American Institute of Physics.

  12. 49 CFR 173.162 - Gallium.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...performance level for transportation by aircraft, and...transport gallium at low temperatures in order...impact resistance at the low temperatures of the...permit the release of carbon dioxide gas. (c...this subchapter. For transportation by aircraft, such...

  13. 49 CFR 173.162 - Gallium.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...performance level for transportation by aircraft, and...transport gallium at low temperatures in order...impact resistance at the low temperatures of the...permit the release of carbon dioxide gas. (c...this subchapter. For transportation by aircraft, such...

  14. Gallium 67 scintigraphy in glomerular disease

    SciTech Connect

    Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.; Rhee, H.L.; Dunea, G.

    1988-12-01

    To evaluate the diagnostic usefulness of gallium 67 scintigraphy in glomerular disease, 45 patients with various glomerulopathies, excluding lupus nephritis and renal vasculitis, were studied. Persistent renal visualization 48 hours after the gallium injection, a positive scintigram, was graded as + (less than), ++ (equal to), and +++ (greater than) the hepatic uptake. Positive scintigrams were seen in ten of 16 cases of focal segmental glomerulosclerosis, six of 11 cases of proliferative glomerulonephritis, and one case of minimal change, and one of two cases of membranous nephropathy; also in three of six cases of sickle glomerulopathy, two cases of diabetic neuropathy, one of two cases of amyloidosis, and one case of mild chronic allograft rejection. The 25 patients with positive scans were younger than the 20 with negative scans (31 +/- 12 v 42 +/- 17 years; P less than 0.01), and exhibited greater proteinuria (8.19 +/- 7.96 v 2.9 +/- 2.3 S/d; P less than 0.01) and lower serum creatinine values (2 +/- 2 v 4.1 +/- 2.8 mg/dL; P less than 0.01). The amount of proteinuria correlated directly with the intensity grade of the gallium image (P less than 0.02), but there was no correlation between the biopsy diagnosis and the outcome of the gallium scan. It was concluded that gallium scintigraphy is not useful in the differential diagnosis of the glomerular diseases under discussion. Younger patients with good renal function and heavy proteinuria are likely to have a positive renal scintigram regardless of the underlying glomerulopathy.

  15. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

  16. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

  17. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

  18. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

  19. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Description of the primary and secondary germanium and gallium subcategory. 421.180...SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180...Description of the primary and secondary germanium and gallium subcategory. The...

  20. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2007. One company in Utah

    E-print Network

    as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $11 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about the gallium recycler-refiner in Utah and a gallium recycler in the United Kingdom jointly purchased

  1. Optical properties and plasmonic response of silver-gallium nanostructures

    NASA Astrophysics Data System (ADS)

    Lereu, A. L.; Lemarchand, F.; Zerrad, M.; Yazdanpanah, M.; Passian, A.

    2015-02-01

    Silver and gallium form an alloy Ag2Ga via a room temperature spontaneous self-assembly that exhibits remarkable mechanical and electrical properties suitable for nanoscale measurements. However, whether photon excitation of plasmons in this emerging nanomaterial is retained or not has not been established. Here, we present a thin film formation of Ag2Ga via a spreading-reactive process of liquid Ga on an Ag film and a characterization of its dielectric function ?(E) = ?1(E) + i?2(E) in the photon energy range 1.42 eV ? E < 4.2 eV. It is observed that while the plasmon damping increases, near an energy of 2.25 eV, the real part of ? exhibits a crossing with respect to that of Ag. Furthermore, the impact of new plasmon supporting materials is discussed and in order to enable further applications in plasmonics, the possibility of photon excitation of surface plasmons in Ag2Ga is studied.

  2. Inflammatory pseudotumor: A gallium-avid mobile mesenteric mass

    SciTech Connect

    Auringer, S.T.; Scott, M.D.; Sumner, T.E. (Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC (USA))

    1991-08-01

    An 8-yr-old boy with a 1-mo history of culture-negative fever and anemia underwent gallium, ultrasound, and computed tomography studies as part of the evaluation of a fever of unknown origin. These studies revealed a mobile gallium-avid solid abdominal mass subsequently proven to be an inflammatory pseudotumor of the mesentery, a rare benign mass. This report documents the gallium-avid nature of this rare lesion and discusses associated characteristic clinical, pathologic, and radiographic features.

  3. Limiting pump intensity for sulfur-doped gallium selenide crystals

    NASA Astrophysics Data System (ADS)

    Guo, J.; Li, D.-J.; Xie, J.-J.; Zhang, L.-M.; Feng, Z.-S.; Andreev, Yu M.; Kokh, K. A.; Lanskii, G. V.; Potekaev, A. I.; Shaiduko, A. V.; Svetlichnyi, V. A.

    2014-05-01

    High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium?selenide).

  4. Photonuclear Reaction Cross Sections for Gallium Isotopes

    E-print Network

    Serkan Akkoyun; Tuncay Bayram

    2014-09-08

    The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron ({\\gamma},xn)) and proton (photo-proton ({\\gamma},xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. According to the results, we have seen that the calculations are in harmony in the limited literature values. Furthermore, the pre-equilibrium and compound process contributions to the total cross-section have been investigated.

  5. Gallium-67 radionuclide imaging in acute pyelonephritis

    SciTech Connect

    Mendez, G.; Morillo, G.; Alonso, M.; Isikoff, M.B.

    1980-01-01

    The symptoms and clinical course of patients with acute pyelonephritis are variable; likewise, urinalysis, blood cultures, and excretory urography may be normal or equivocal. The ability of gallium-67 to accumulate in areas of active inflammation was useful in the diagnosis of acute pyelonephritis in 12 cases. A multiplane tomographic scanner was used for imaging four of these patients. Initial experience with this scanner is also discussed.

  6. Porous gallium arsenide with arsenic clusters

    Microsoft Academic Search

    Yu. N. Buzynin; S. A. Gusev; Yu. N. Drozdov; A. V. Murel

    2000-01-01

    It is for the first time that the possibility is demonstrated of preparing gallium arsenide with arsenic clusters under conditions\\u000a of annealing of its porous layers obtained by electrochemical etching. It is found that the clusters are concentrated in porous\\u000a layer barriers, their size ranges from 1 to 10 nm, and the density reaches 41018 cm?3. Under conditions of annealing

  7. A Gallium multiphase equation of state

    SciTech Connect

    Crockett, Scott D [Los Alamos National Laboratory; Greeff, Carl [Los Alamos National Laboratory

    2009-01-01

    A new SESAME multiphase Gallium equation of state (EOS) has been developed. The equation of state includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniol data. We also explore the possibility of re-freezing via dynamic means such as isentropic and shock compression.

  8. High-dose gallium imaging in lymphoma

    SciTech Connect

    Anderson, K.C.; Leonard, R.C.; Canellos, G.P.; Skarin, A.T.; Kaplan, W.D.

    1983-08-01

    The role of gallium-67 imaging in the management of patients with lymphoma, traditionally assessed using low tracer doses and the rectilinear scanner, was assessed when using larger doses (7 to 10 mCi) and a triple-peak Anger camera. Gallium scan results in 51 patients with non-Hodgkin's lymphoma and 21 patients with Hodgkin's disease were compared with simultaneous radiologic, clinical, and histopathologic reports. Subsequent disease course was also evaluated in light of radionuclide findings. Sensitivity and specificity of the scans were 0.90 or greater for both non-Hodgkin's lymphoma and Hodgkin's disease, and overall accuracy by site was 96 percent. Although there are insufficient numbers of pretreatment scans to allow any conclusions, our data suggest that newer approaches to gallium scanning in treated patients are (1) highly specific in all lymphomas and most sensitive in high-grade non-Hodgkin's lymphoma and Hodgkin's disease; (2) valuable in assessing the mediastinum in both non-Hodgkin's lymphoma and Hodgkin's disease; and (3) helpful adjuncts to computed tomographic scanning and ultrasonography in assessing abdominal node disease.

  9. P-n junctions formed in gallium antimonide

    NASA Technical Reports Server (NTRS)

    Clough, R.; Richman, D.; Tietjen, J.

    1970-01-01

    Vapor phase deposition process forms a heavily doped n-region on a melt-grown p-type gallium antimonide substrate. HCl transports gallium to the reaction zone, where it combines with antimony hydride and the dopant carrier, hydrogen telluride. Temperatures as low as 400 degrees C are required.

  10. Standard Reference Material 1751: Gallium Melting-Point Standard

    E-print Network

    Standard Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse NIST Special Publication 260-157 #12;#12;NIST Special Publication 260-157 XXXX Standard Reference Material 1751: Gallium Melting-Point Standard Gregory F. Strouse Chemical Science and Technology Laboratory Process Measurements

  11. Gallium scintigraphy in bone infarction. Correlation with bone imaging

    SciTech Connect

    Armas, R.R.; Goldsmith, S.J.

    1984-01-01

    The appearance of gallium-67 images in bone infarction was studied in nine patients with sickle cell disease and correlated with the bone scan findings. Gallium uptake in acute infarction was decreased or absent with a variable bone scan uptake, and normal in healing infarcts, which showed increased uptake on bone scan. The significance of these findings is discussed.

  12. Gallium scintigraphic pattern in lung CMV infections

    SciTech Connect

    Ganz, W.I.; Cohen, D.; Mallin, W. [Univ. of Miami School of Medicine, FL (United States)] [and others

    1994-05-01

    Due to extensive use of prophylactic therapy for Pneumonitis Carinii Pneumonia (PCP), Cytomegalic Viral (CMV) infection may now be the most common lung infection in AIDS patients. This study was performed to determine Gallium-67 patterns in AIDS patients with CMV. Pathology reports were reviewed in AIDS patients who had a dose of 5 to 10 mCi of Gallium-67 citrate. Analysis of images were obtained 48-72 hours later of the entire body was performed. Gallium-67 scans in 14 AIDS patients with biopsy proven CMV, were evaluated for eye, colon, adrenal, lung and renal uptake. These were compared to 40 AIDS patients without CMV. These controls had infections including PCP, Mycobacterial infections, and lymphocytic interstitial pneumonitis. 100% of CMV patients had bowel uptake greater than or equal to liver. Similar bowel activity was seen in 50% of AIDS patients without CMV. 71% had intense eye uptake which was seen in only 10% of patients without CMV. 50% of CMV patients had renal uptake compared to 5% of non-CMV cases. Adrenal uptake was suggested in 50%, however, SPECT imaging is needed for confirmation. 85% had low grade lung uptake. The low grade lung had perihilar prominence. The remaining 15% had high grade lung uptake (greater than sternum) due to superimposed PCP infection. Colon uptake is very sensitive indicator for CMV infection. However, observing eye, renal, and or adrenal uptake improved the diagnostic specificity. SPECT imaging is needed to confirm renal or adrenal abnormalities due to intense bowel activity present in 100% of cases. When high grade lung uptake is seen superimposed PCP is suggested.

  13. Nanopipes in gallium nitride nanowires and rods.

    PubMed

    Jacobs, Benjamin W; Crimp, Martin A; McElroy, Kaylee; Ayres, Virginia M

    2008-12-01

    Gallium nitride nanowires and rods synthesized by a catalyst-free vapor-solid growth method were analyzed with cross section high-resolution transmission electron microscopy. The cross section studies revealed hollow core screw dislocations, or nanopipes, in the nanowires and rods. The hollow cores were located at or near the center of the nanowires and rods, along the axis of a screw dislocation. The formation of the hollow cores is consistent with effect of screw dislocations with giant Burgers vector predicted by Frank. PMID:19367802

  14. Alloy materials

    DOEpatents

    Hans Thieme, Cornelis Leo (Westborough, MA); Thompson, Elliott D. (Coventry, RI); Fritzemeier, Leslie G. (Acton, MA); Cameron, Robert D. (Franklin, MA); Siegal, Edward J. (Malden, MA)

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

  15. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2008. One company in Utah

    E-print Network

    as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $23 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about

  16. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2009. One company in Utah

    E-print Network

    as a percentage of reported consumption 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $14 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about

  17. (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2003. One company in

    E-print Network

    $4 million, most of which was low-purity material. Gallium arsenide (GaAs) and gallium nitride (GaN in optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes, photodetectors, and solar cells

  18. Fabrication, performance and degradation mechanism of aluminum gallium nitride/gallium nitride heterostructure field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kim, Hyungtak

    Gallium nitride (GaN) has attracted a lot of attention as the next generation of semiconductor material for microwave power application. The unique and superior material properties of GaN and its heterostructure, such as excellent transport property, high breakdown voltage and sheet carrier concentration, and thermal and mechanical stabilities, enable AlGaN/GaN heterostructure field effect transistors (HFETs) to deliver unprecedented levels of microwave power performance. Potential applications include ultra-wide bandwidth communications and radar systems, wireless base stations, and communications satellites. Tremendous efforts to realize the potential of Al-GaN/GaN HFETs have been made over the last decade focusing on improving microwave power performance via optimizing material growth and semiconductor processing technologies. As the device performance is getting mature, the device's reliability becomes a major concern for manufacturability of commercially available AlGaN/GaN HFETs. However, comprehensive study on the reliability of these devices is still lacking. This dissertation describes the fabrication, performance and degradation characteristics and mechanism of AlGaN/GaN HFETs. The devices were fabricated with alloyed Ti/Al/Ti/Au ohmic contact and Ni/Au mushroom gate contact using E-beam lithography. The device's microwave performance was significantly improved after SiN passivation due to reduced surface effects. Several degradation modes, primarily a decrease of the output current and microwave output power density, were observed under various electrical stress tests including high current stress, high field stress, and RF overdrive. To further investigate the physical mechanism of observed degradations, SiN passivation, pulsed IV (gate lag), low frequency noise measurements, deep level transient spectroscopy (DLTS), and scanning kelvin probe microscopy (SKPM) have all been employed with hot electron stress testing. The results clearly demonstrated that charge accumulation and trap creation at the semiconductor surface and interface induced by hot electron effects are responsible for observed degradation.

  19. Gallium scanning in lymphoid interstitial pneumonitis of children with AIDS

    SciTech Connect

    Schiff, R.G.; Kabat, L.; Kamani, N.

    1987-12-01

    Lymphoid interstitial pneumonitis (LIP) is a frequent pulmonary complication in the child with the acquired immune deficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection. We report the gallium scan findings in two children with AIDS and LIP. Gallium scintigraphy in both children demonstrated increased radionuclide concentration throughout the lungs, a pattern indistinguishable scintigraphically from that of Pneumocystis carinii pneumonia (PCP). This should alert nuclear medicine practitioners and referring physicians to another cause of diffusely increased gallium uptake in the lungs of patients with AIDS.

  20. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2012. One company in Utah

    E-print Network

    ­4908, bjaskula@usgs.gov] #12;59 GALLIUM In 2012, the worldwide LED market, a significant driver for GaN.S. gallium consumption, were valued at about $32 million. Gallium arsenide (GaAs) and gallium nitride (GaN conditions continued to improve for GaAs- and GaN-based products in 2012. GaAs demand, while still driven

  1. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally,

    E-print Network

    of a strong LED-based backlighting market, which failed to materialize. Global demand for GaAs- and GaN.S. gallium consumption, were valued at about $16 million. Gallium arsenide (GaAs) and gallium nitride (GaN to the large power-handling capabilities, high-switching frequencies, and higher voltage capabilities of GaN

  2. All-optical modulation in gallium arsenide integrated optical waveguides

    SciTech Connect

    McWright, G.; Ross, B.; Guthreau, W.; Lafaw, D.; Lowry, M.; Tindall, W.

    1988-01-27

    We have investigated all-optical modulators in gallium arsenide integrated optical waveguides; these modulators use electron-hole pair generation to alter the propagation characteristics of a guided light beam. 6 refs., 6 figs.

  3. Computer simulation of radiation damage in gallium arsenide

    NASA Technical Reports Server (NTRS)

    Stith, John J.; Davenport, James C.; Copeland, Randolph L.

    1989-01-01

    A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.

  4. Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

    2007-01-01

    A low-energy gallium plasma source is used to perform a spatially and temporally broad spectroscopic survey in the 220-520 nm range. Neutral, singly, and doubly ionized gallium are present in a 20 J, 1.8 kA (peak) arc discharge operating with a central cathode. When the polarity of the inner electrode is reversed the discharge current and arc voltage waveforms remain similar. Utilizing a central anode configuration, multiple Ga lines are absent in the 270-340 nm range. In addition, neutral and singly ionized Fe spectral lines are present, indicating erosion of the outer electrode. With graphite present on the insulator to facilitate breakdown, line emission from the gallium species is further reduced and while emissions from singly and doubly ionized carbon atoms and molecular carbon (C2) radicals are observed. These data indicate that a significant fraction of energy is shifted from the gallium and deposited into the various carbon species.

  5. Generator for ionic gallium-68 based on column chromatography

    DOEpatents

    Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

    1981-01-01

    A physiologically acceptable solution of gallium-68 fluorides, having an activity of 0.1 to 50 millicuries per milliliter of solution is provided. The solution is obtained from a generator comprising germanium-68 hexafluoride bound to a column of an anion exchange resin which forms gallium-68 in situ by eluting the column with an acid solution to form a solution containing .sup.68 Ga-fluorides. The solution then is neutralized prior to administration.

  6. Complexometric determination of gallium with calcein blue as indicator

    USGS Publications Warehouse

    Elsheimer, H.N.

    1967-01-01

    A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1 % and a relative standard deviation of about 0.4% for 10 mg of gallium. ?? 1967.

  7. Wafer bonding of gallium arsenide on sapphire

    NASA Astrophysics Data System (ADS)

    Kopperschmidt, P.; Kästner, G.; Senz, S.; Hesse, D.; Gösele, U.

    Three-inch (100) gallium arsenide wafers were bonded to ( 1/line{1} 02) sapphire in a micro-cleanroom at room temperature under hydrophilic or hydrophobic surface conditions. Subsequent heating up to 500 °C increased the bond energy of the GaAs-on-sapphire (GOS) wafer pair close to the fracture energy of the bulk material. The bond energy was measured as a function of the temperature. Since the thermal expansion coefficients of GaAs and sapphire are close to each other, the bonded wafer pair is stable against thermal treatment and quenching in liquid nitrogen. During heating in different gas atmospheres, macroscopic interface bubbles and microscopic imperfections were formed within the bonding interface, which were analysed by transmission electron microscopy (TEM). These interface bubbles can be prevented by hydrophobic bonding in a hydrogen atmosphere.

  8. Optical properties of gadolinium gallium garnet.

    PubMed

    Wood, D L; Nassau, K

    1990-09-01

    The refractive index, the temperature coefficient of the refractive index, and the optical transparency of gadolinium gallium garnet are reported as a function of wavelength from the near UV to the middle IR. The materialis transparent enough for good optical components between 0.36 and 6.0 microm, and the refractive index ranges from 2.0 at the UV end to 1.8 at the IR end of the spectrum. The wavelength dependence of index is expressed as a three-term Sellmeier formula with agreement better than two parts in the fourth decimal between calculated and experimental values. Variations in composition depending on growth from various melts (e.g., stoichiometric vs congruent) have no effect on the optical parameters at this level of precision. PMID:20567472

  9. Cavity optomechanics in gallium phosphide microdisks

    SciTech Connect

    Mitchell, Matthew; Barclay, Paul E., E-mail: pbarclay@ucalgary.ca [Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada); Hryciw, Aaron C. [National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada)

    2014-04-07

    We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8?×?10{sup 5} and mode volumes <10(?/n){sup 3}, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0?×?10{sup 4} intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5??m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2??30?kHz for the fundamental mechanical radial breathing mode at 488?MHz.

  10. Direct band gap wurtzite gallium phosphide nanowires.

    PubMed

    Assali, S; Zardo, I; Plissard, S; Kriegner, D; Verheijen, M A; Bauer, G; Meijerink, A; Belabbes, A; Bechstedt, F; Haverkort, J E M; Bakkers, E P A M

    2013-04-10

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  11. Direct Band Gap Wurtzite Gallium Phosphide Nanowires

    PubMed Central

    2013-01-01

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  12. Cathodoluminescence spectra of gallium nitride nanorods

    PubMed Central

    2011-01-01

    Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896

  13. Gallium arsenide solar array subsystem study

    NASA Technical Reports Server (NTRS)

    Miller, F. Q.

    1982-01-01

    The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

  14. In-situ X-ray photoelectron spectroscopy study of supported gallium oxide

    NASA Astrophysics Data System (ADS)

    Serykh, Alexander I.; Amiridis, Michael D.

    2010-06-01

    In-situ XPS study of supported gallium oxide catalysts prepared by impregnation of different metal oxides supports (SiO 2, ?-Al 2O 3, TiO 2, and MgO) has been performed. It has been found that the formation of metallic gallium takes place upon high-temperature reduction of the catalysts in flowing hydrogen. Relative concentrations of metallic gallium were most high in the cases of alumina- and titania-supported catalysts. It was suggested that interaction of gallium oxide with a support surface favors the formation of metallic gallium upon high-temperature reduction. A possible mechanism of metallic gallium formation upon the reduction is discussed.

  15. Inhalation developmental toxicology studies: Gallium arsenide in mice and rats

    SciTech Connect

    Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

    1990-12-01

    Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

  16. Role of the gallium scan in Hodgkin's disease

    SciTech Connect

    Hagemeister, F.B.; Fesus, S.M.; Lamki, L.M.; Haynie, T.P. (Univ. of Texas, M.D. Anderson Cancer Center, Houston (USA))

    1990-03-01

    The reports of 240 gallium scans on 165 patients with Hodgkin's disease were reviewed to compare results with higher doses with those in earlier studies that employed lower doses. Tracer concentrations in specific sites were correlated with radiologic and pathologic reports and with the clinical courses of the patients studied. There were no significant differences in overall results between newer and older gallium scanning techniques. For untreated patients, the overall sensitivity was only 64%, but the overall specificity was 98%. For untreated patients and for patients with relapsing disease, the presence of gallium concentration in a specific site was highly predictive of active Hodgkin's disease at that site. However, for routine follow-up of treated patients, 95% of unsuspected relapses were missed by the scan, indicating the limited usefulness of negative scan results in this setting. For patients with residual abnormalities after therapy, demonstrated by other radiographic means, increased uptake of gallium in abdominal or peripheral lymph nodes also indicated active disease, although lack of uptake was reliable only in the mediastinum. Based on these results, it appears that the higher doses used in this study have not substantially improved the role of gallium scanning in this disease. Although it is potentially useful in providing confirmatory data at diagnosis or in patients with new or residual objective abnormalities after treatment, routine use of gallium scanning in Hodgkin's disease is not recommended.

  17. Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions––effective laser media

    Microsoft Academic Search

    Yu. K Voronko; A. A Sobol; A. Ya Karasik; N. A Eskov; P. A Rabochkina; S. N Ushakov

    2002-01-01

    The results of spectroscopy and laser action of disordered calcium niobium gallium (CNGG) and calcium lithium niobium gallium (CLNGG) garnets doped with Nd3+, Eu3+, Er3+, Ho3+ and Tm3+ were displayed. The structure and some optical and physical properties of CNGG and CLNGG-crystals were studied. Activator centers construction and the mechanism of inhomogeneous broadening and splitting of spectral lines of rare

  18. Magnetic susceptibility of CoFeBSiNb alloys in liquid state

    NASA Astrophysics Data System (ADS)

    Sidorov, V.; Hosko, J.; Mikhailov, V.; Rozkov, I.; Uporova, N.; Svec, P.; Janickovic, D.; Matko, I.; Svec, P., Sr.; Malyshev, L.

    2014-03-01

    The influence of small additions of gallium and antimony on magnetic susceptibility of the bulk glass forming Co47Fe20.9B21.2Si4.6Nb6.3 alloy was studied in a wide temperature range up to 1830 K by the Faraday's method. The undercooling for all the samples was measured experimentally. Both Ga and Sb additions were found to increase liquidus and solidification temperatures. However, gallium atoms strengthen interatomic interaction in the melts, whereas antimony atoms reduce it.

  19. The effect of free gallium and gallium in liposomes on cytokine and nitric oxide secretion from macrophage-like cells in vitro.

    PubMed

    Makkonen, N; Hirvonen, M R; Savolainen, K; Lapinjoki, S; Mönkkönen, J

    1995-12-01

    The aim of this study was to evaluate the effect of gallium nitrate, gallium-nitrilotriacetate (NTA) complex, and liposomal gallium-NTA on IL-6, TNF alpha, and nitric oxide (NO) release from activated macrophages. In addition, the expression of the inducible nitric oxide synthase (iNOS) was determined. Gallium inhibited dose-dependently the secretion of IL-6, TNF alpha, and NO from the LPS-induced macrophage-like RAW 264 cells. Encapsulation of gallium in negatively charged DSPG-liposomes increased its potency 10-50 times and 7-11 times compared to free gallium nitrate and gallium-NTA, respectively. Neither non-loaded liposomes nor NTA alone inhibited cytokine or NO secretion, demonstrating that the observed effects originated from gallium. Liposomal gallium-NTA inhibited the expression of iNOS by the macrophages, while other formulations of gallium had no effect. Thus, gallium, when delivered properly, suppresses macrophage functions by inhibiting the release of inflammatory mediators from the cells. PMID:8788232

  20. Annealing behaviour of P-type layers formed by ion-implantation of gallium in silicon

    Microsoft Academic Search

    K. Bulthuis; R. Tree

    1969-01-01

    The number of charge carriers in gallium implanted as a function of annealing temperature is related to the formation of neutral complexes. Corresponding differences in penetration depth of gallium atoms are noted.

  1. Application of ultrasound in solvent extraction of nickel and gallium

    SciTech Connect

    Pesic, B.

    1996-07-01

    The effects of ultrasound on the rate of solvent extraction of nickel with Lix 65N and Lix 70, and gallium with Kelex 100 were investigated. These solvent extraction systems are noted by their sluggish nature. Low frequency (20 kHz) ultrasound increased the rates of extraction of nickel by factors of four to seven. The ultrasound had no effect on the final chemical equilibrium. Gallium extraction rates were enhanced with the use of ultrasound by as much as a factor of 15. Again, the ultrasound had no effect on extraction equilibrium. For both nickel and gallium, the enhanced rates were attributed to increased interfacial surface area associated with ultrasonically induced cavitation and microdroplet formation. The stability of the microdroplets permitted intermittent application of ultrasound with corresponding decreases in ultrasonic energy requirements. The lowest energy consumption was observed with short (0.25 to 5 s) bursts of high power (41 to 61 W) ultrasonic inputs. The study also provided insight into the factors that affect the complex extraction of gallium from sodium aluminate solutions. The rate controlling step was found to be the dehydration of the gallate ion, Ga(OH)4, and the first complex formation between gallium and Kelex 100. Sodium was found to enhance the extraction rate up to a point, beyond which increased concentration was detrimental. Increasing aluminum concentration was found to slow extraction rates. Modifiers and diluents were shown to markedly affect extraction rates even without ultrasound. Ketone modifiers, particularly 2-undecanone, when used with Kermac 470B or Escaid 200 diluents enhanced extraction rates of gallium to the point that the use of ultrasound provided no additional benefits. The positive effects of ketone modifiers for the solvent extraction of gallium had not been previously reported.

  2. Characteristics of epitaxial garnets grown by CVD using single metal alloy sources. [Chemical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Besser, P. J.; Hamilton, T. N.; Mee, J. E.; Stermer, R. L.

    1974-01-01

    Single metal alloys have been explored as the cation source in the chemical vapor deposition (CVD) of iron garnets. Growth of good quality single crystal garnet films containing as many as five different cations has been achieved over a wide range of deposition conditions. The relationship of film composition to alloy compositions and deposition conditions has been determined for several materials. By proper choice of the alloy composition and the deposition conditions, uncrazed deposits were grown on (111) gadolinium gallium garnet (GGG) substrates. Data on physical, magnetic and optical properties of representative films is presented and discussed.

  3. Gallium a unique anti-resorptive agent in bone: Preclinical studies on its mechanisms of action

    SciTech Connect

    Bockman, R.; Adelman, R.; Donnelly, R.; Brody, L.; Warrell, R. (Hospital for Special Surgery, New York, NY (USA)); Jones, K.W. (Brookhaven National Lab., Upton, NY (USA))

    1990-01-01

    The discovery of gallium as a new and unique agent for the treatment of metabolic bone disorders was in part fortuitous. Gallium is an exciting new therapeutic agent for the treatment of pathologic states characterized by accelerated bone resorption. Compared to other therapeutic metal compounds containing platinum or germanium, gallium affects its antiresorptive action without any evidence of a cytotoxic effect on bone cells. Gallium is unique amongst all therapeutically available antiresorptive agents in that it favors bone formation. 18 refs., 1 fig.

  4. Gallium based low-interaction anions

    DOEpatents

    King, Wayne A. (Santa Fe, NM); Kubas, Gregory J. (Santa Fe, NM)

    2000-01-01

    The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

  5. Pure silver ohmic contacts to N- and P- type gallium arsenide materials

    DOEpatents

    Hogan, Stephen J. (Golden, CO)

    1986-01-01

    Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

  6. Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials

    DOEpatents

    Hogan, S.J.

    1983-03-13

    Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

  7. Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting

    E-print Network

    Rogers, John A.

    #12;Unusual strategies for using indium gallium nitride grown on silicon (111) for solid with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements solid-state lighting transfer printing Indium gallium nitride-based (InGaN) blue light emitting diodes

  8. Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting

    E-print Network

    Choquette, Kent

    Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements solid-state lighting transfer printing Indium gallium nitride-based (InGaN) blue light emitting diodes

  9. LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM

    E-print Network

    Paris-Sud XI, Université de

    703 LE JOURNAL DE PHYSIQUE STARK BROADENING OF NEUTRAL AND SINGLY IONIZED GALLIUM AND INDIUM LINES, accepte Ie 19 fivrier 1987) Résumé : Les élargissements Stark de raies du gallium et de l'indium neutre cathode liquide utilisant un mélange sodium-indium ou potassium-gallium, la densité electronique pouvant

  10. Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells

    E-print Network

    Rockett, Angus

    Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with a larger number of vacancies, that facilitates indium and gallium diffusion, in the sodium free films

  11. Fabrication of Large-Area Graphene Using Liquid Gallium and Its Electrical Properties

    Microsoft Academic Search

    Jun-ichi Fujita; Yosuke Miyazawa; Ryuichi Ueki; Mio Sasaki; Takeshi Saito

    2010-01-01

    We demonstrated a new process for synthesizing a graphene sheet at the interface between solid amorphous carbon and liquid gallium. The insolubility of carbon in gallium strongly restricted the depth of graphitization, but a multilayered graphene sheet having four to six layers of graphene was produced over the entire area of the interface immediately beneath the liquid gallium. We also

  12. Realization of the Gallium Triple Point at NMIJ/AIST

    NASA Astrophysics Data System (ADS)

    Nakano, T.; Tamura, O.; Sakurai, H.

    2008-02-01

    The triple point of gallium has been realized by a calorimetric method using capsule-type standard platinum resistance thermometers (CSPRTs) and a small glass cell containing about 97 mmol (6.8 g) of gallium with a nominal purity of 99.99999%. The melting curve shows a very flat and relatively linear dependence on 1/ F in the region from 1/ F = 1 to 1/ F = 20 with a narrow width of the melting curve within 0.1 mK. Also, a large gallium triple-point cell was fabricated for the calibration of client-owned CSPRTs. The gallium triple-point cell consists of a PTFE crucible and a PTFE cap with a re-entrant well and a small vent. The PTFE cell contains 780 g of gallium from the same source as used for the small glass cell. The PTFE cell is completely covered by a stainless-steel jacket with a valve to enable evacuation of the cell. The melting curve of the large cell shows a flat plateau that remains within 0.03 mK over 10 days and that is reproducible within 0.05 mK over 8 months. The calibrated value of a CSPRT obtained using the large cell agrees with that obtained using the small glass cell within the uncertainties of the calibrations.

  13. Preliminary Spectroscopic Measurements for a Gallium Electromagnetic (GEM) Thruster

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

    2007-01-01

    As a propellant option for electromagnetic thrusters, liquid ,gallium appears to have several advantages relative to other propellants. The merits of using gallium in an electromagnetic thruster (EMT) are discussed and estimates of discharge current levels and mass flow rates yielding efficient operation are given. The gallium atomic weight of 70 predicts high efficiency in the 1500-2000 s specific impulse range, making it ideal for higher-thrust, near-Earth missions. A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma and estimate electron temperature. The spectra show that neutral, singly, and doubly ionized gallium species are present in a 20 J, 1.8 kA (peak) are discharge. With graphite present on the insulator to facilitate breakdown, singly and doubly ionized carbon atoms are also present, and emission is observed from molecular carbon (CZ) radicals. A determination of the electron temperature was attempted using relative emission line data, and while the spatially and temporally averaged, spectra don't fit well to single temperatures, the data and presence of doubly ionized gallium are consistent with distributions in the 1-3 eV range.

  14. Self-Diffusion in gallium arsenide

    NASA Astrophysics Data System (ADS)

    Palfrey, H. D.; Brown, M.; Willoughby, A. F. W.

    1983-09-01

    The self-diffusion of arsenic in gallium arsenide has been studied over the temperature range 1000 to 1075?C using radiotracer techniques.76As was diffused into GaAs samples at known arsenic pressures in sealed capsules. After diffusion, layers were removed from the surface using anodic oxidation followed by oxide dissolution. Diffusion profiles were obtained by measuring the76As concentration in each sectioned layer by ?-radiation counting. Diffusion coefficients at PAs 2 = 0.75 atm and over the temperature range 1000 to 1050?C were found to be 5.2 × 10-16cm2s-1 to 1.5 × 10-15 cm2s-1, leading to an activation energy of the order of 3.0± 0.04 eV and a pre-exponential factor of 5.5 × l0-4 ± 2.4 × 10-4 cm2s-1. Diffusion coefficients at PAs 2 =3.0 atm were found to be 5.5 × 10-15 and 9.8 × 10-16 cm2 s-1 at 1050 and 1075?C, respectively. Results are discussed in terms of native point defect equilibria with the arsenic gaseous phase, and with respect to other work. It is deduced from our observed arsenic pressure dependence of the arsenic diffusivity that the most likely diffusion mechanism

  15. Gallium arsenide photo-field emission

    NASA Astrophysics Data System (ADS)

    Vecchione, Theodore

    The development of monochromatic ultrafast electron sources with high brightness and high coherence is increasingly important in both time-resolved and energy-resolved electron microscopy. This work details the fabrication of intrinsic Gallium-Arsenide photo-field emitters and their evaluation as potential source candidates. The emitters were prepared via chemical etching and vacuum heat cleansing of cleaved wafer shards that had been mounted in refractory metal holders. Data were recorded in the form of field emission images, current-voltage characteristic curves and energy distribution curves under several different thermal and illumination conditions. As expected, illumination increased emission by 3 orders of magnitude. However a much larger than expected energy distribution of 0.76 eV was observed. This result invalidated presumptions that the band structure would produce a maximum energy width equal to the energy bandgap minus the photon energy. Following the experiment a Spicer-like 3-step model was used to explain this discrepancy. In the model the energy broadening is attributed to a combination of bulk thermal effects and surface band bending. Using this model, predictions are made as to the performance of a similar photo-field emitter that should better fulfill the needs of both time-resolved and energy-resolved electron microscopy.

  16. Synthesis and characterization of gallium colloidal nanoparticles.

    PubMed

    Meléndrez, M F; Cárdenas, G; Arbiol, J

    2010-06-15

    In this work, gallium colloidal nanoparticles (Ga-Nps) were synthesized by chemical liquid deposition (CLD). This method involved the deposition of metallic atoms with organic solvents (THF, acetone and 2-propanol) in a freezing matrix of the solvent at 77K, in order to obtain core-shell Ga-Nps which were characterized by: FT-IR, UV-Vis, TEM, SAED and electrophoretic mobility measurements. TEM images revealed a wide distribution of the apparent size of the particles and apparent average size of 5.65, 8.11 and 13.87 nm for Ga-Nps obtained with 2-propanol, THF and acetone, respectively. UV spectra showed absorption bands of metal plasmons, interesting quantum size effects and plasmon absorption bands of particles aggregated to lambda(280) and lambda(325). Electrophoretic mobility allowed to evidence that nanoparticles had a negative charge as well as to observe that the zeta potential of the colloidal dispersions decreased over time, showing a significant tendency to the aggregation of Ga-Nps. The importance of the functionalization of metal nanoparticles with high dielectric constant solvents in the stabilization of colloidal systems was also observed. FT-IR spectroscopy revealed that the interaction of Ga surface with the solvent possibly produces a (GaC) bond. Experimental details, structural and thermal stability studies were also analyzed in this work. PMID:20378122

  17. Gallium nitride micromechanical resonators for IR detection

    NASA Astrophysics Data System (ADS)

    Rais-Zadeh, Mina

    2012-06-01

    This paper reports on a novel technology for low-noise un-cooled detection of infrared (IR) radiation using a combination of piezoelectric, pyroelectric, electrostrictive, and resonant effects. The architecture consists of a parallel array of high-Q gallium nitride (GaN) micro-mechanical resonators coated with an IR absorbing nanocomposite. The nanocomposite absorber converts the IR energy into heat with high efficiency. The generated heat causes a shift in frequency characteristics of the GaN resonators because of pyroelectric effect. IR detection is achieved by sensing the shift in the resonance frequency and amplitude of the exposed GaN resonator as compared to a reference resonator that is included in the array. This architecture offers improved signal to noise ratio compared with conventional pyroelectric detectors as the resonant effect reduces the background noise and improves sensitivity, enabling IR detection with NEDTs below 5 mK at room temperature. GaN is chosen as the resonant material as it possesses high pyroelectric, electrostrictive, and piezoelectric coefficients and can be grown on silicon substrates for low-cost batch fabrication. Measured results of a GaN IR detector prototype and a thin-film nanocomposite IR absorber are presented in this paper.

  18. Photoluminescence study of gallium vacancy defects in gallium arsenide irradiated by relativistic protons

    SciTech Connect

    Carlone, C.; Parenteau, M. [Univ. de Sherbrooke, Quebec (Canada). Dept. de Physique] [Univ. de Sherbrooke, Quebec (Canada). Dept. de Physique; Houdayer, A.; Hinrichsen, P. [Univ. de Montreal, Quebec (Canada). Dept. de Physique] [Univ. de Montreal, Quebec (Canada). Dept. de Physique; Vincent, J. [TRIUMF, Vancouver, British Columbia (Canada)] [TRIUMF, Vancouver, British Columbia (Canada)

    1997-12-01

    Epitaxially grown n-type gallium arsenide films, doped with silicon to concentrations of 2 {times} 10{sup 15} and 2 {times} 10{sup 16} cm{sup {minus}3} were exposed at room temperature to 200, 350, and 500 MeV proton irradiation at fluences of 3 {times} 10{sup 11}, 10{sup 12}, 10{sup 13}, 3 {times} 10{sup 13}, 10{sup 14} and 10{sup 15} cm{sup {minus}2}. The effects of the irradiation were determined through low temperature continuous photoluminescence spectroscopy. Two radiation-induced donor-to-acceptor transitions were observed. The one at 1.476 eV has been associated to the gallium vacancy acceptor (V{sub Ga}) and the other at 1.482 eV to the silicon at the arsenic site acceptor (Si{sub As}). The relative introduction rate of these two defects has been measured in the irradiated samples before and after annealing at 550 C for 30 minutes. The introduction rates are higher than those predicted by relativistic elastic scattering cross-section theory in the energy range studied here. The authors conclude that inelastic scattering contributes to the cross-section. The introduction rates are lower than nonionizing energy loss (NIEL) calculations in the 200 to 500 MeV energy range. They suggest that the proton inelastic scattering parameter used in NIEL needs revision. The relativistic inelastic scattering formula is closer to experiment than present NIEL calculations.

  19. Gallium plasmonics: deep subwavelength spectroscopic imaging of single and interacting gallium nanoparticles.

    PubMed

    Knight, Mark W; Coenen, Toon; Yang, Yang; Brenny, Benjamin J M; Losurdo, Maria; Brown, April S; Everitt, Henry O; Polman, Albert

    2015-02-24

    Gallium has recently been demonstrated as a phase-change plasmonic material offering UV tunability, facile synthesis, and a remarkable stability due to its thin, self-terminating native oxide. However, the dense irregular nanoparticle (NP) ensembles fabricated by molecular-beam epitaxy make optical measurements of individual particles challenging. Here we employ hyperspectral cathodoluminescence (CL) microscopy to characterize the response of single Ga NPs of various sizes within an irregular ensemble by spatially and spectrally resolving both in-plane and out-of-plane plasmonic modes. These modes, which include hybridized dipolar and higher-order terms due to phase retardation and substrate interactions, are correlated with finite difference time domain (FDTD) electrodynamics calculations that consider the Ga NP contact angle, substrate, and native Ga/Si surface oxidation. This study experimentally confirms previous theoretical predictions of plasmonic size-tunability in single Ga NPs and demonstrates that the plasmonic modes of interacting Ga nanoparticles can hybridize to produce strong hot spots in the ultraviolet. The controlled, robust UV plasmonic resonances of gallium nanoparticles are applicable to energy- and phase-specific applications such as optical memory, environmental remediation, and simultaneous fluorescence and surface-enhanced Raman spectroscopies. PMID:25629392

  20. Native gallium adatoms discovered on atomically-smooth gallium nitride surfaces at low temperature.

    PubMed

    Alam, Khan; Foley, Andrew; Smith, Arthur R

    2015-03-11

    In advanced compound semiconductor devices, such as in quantum dot and quantum well systems, detailed atomic configurations at the growth surfaces are vital in determining the structural and electronic properties. Therefore, it is important to investigate the surface reconstructions in order to make further technological advancements. Usually, conventional semiconductor surfaces (e.g., arsenides, phosphides, and antimonides) are highly reactive due to the existence of a high density of group V (anion) surface dangling bonds. However, in the case of nitrides, group III rich growth conditions in molecular beam epitaxy are usually preferred leading to group III (Ga)-rich surfaces. Here, we use low-temperature scanning tunneling microscopy to reveal a uniform distribution of native gallium adatoms with a density of 0.3%-0.5% of a monolayer on the clean, as-grown surface of nitrogen polar GaN(0001?) having the centered 6 × 12 reconstruction. Unseen at room temperature, these Ga adatoms are strongly bound to the surface but move with an extremely low surface diffusion barrier and a high density saturation coverage in thermodynamic equilibrium with Ga droplets. Furthermore, the Ga adatoms reveal an intrinsic surface chirality and an asymmetric site occupation. These observations can have important impacts in the understanding of gallium nitride surfaces. PMID:25656811

  1. Characterization of oxygen deficient gallium oxide films grown by PLD

    NASA Astrophysics Data System (ADS)

    Petitmangin, A.; Gallas, B.; Hebert, C.; Perrière, J.; Binet, L.; Barboux, P.; Portier, X.

    2013-08-01

    X-ray photoelectron spectroscopy and transmission electron microscopy have been used to investigate the nature and characteristics of oxygen deficient gallium oxide films grown by pulsed laser deposition. The presence of the Ga3+ and Ga+ oxidation states, together with metallic Ga0 was observed by XPS in Ga2O2.3 sub-oxide films. TEM images reveal the presence in a Ga2O3 matrix of gallium oblong particles whose structure studied at nitrogen temperature was found to correspond to the ? monoclinic phase of metallic gallium. These results characterize the formation of nanocomposite films with Ga metallic clusters embedded in a stoichiometric Ga2O3 matrix. The nanocomposite film formation is due to a phase separation in the metastable sub-stoichiometric Ga2O2.3 film.

  2. The Soviet-American gallium experiment at Baksan

    SciTech Connect

    Abazov, A. I.; Abdurashitov, D. N.; Anosov, O. L.; Danshin, S. N.; Eroshkina, L. A.; Faizov, E. L.; Gavrin, V. N.; Kalikhov, A. V.; Knodel, T. V.; Knyshenko, I. I.; Kornoukhov, V. N.; Mezentseva, S. A.; Mirmov, I. N.; Ostrinsky, A. I.; Petukhov, V. V; Pshukov, A. M.; Revzin, N. Ye; Shikhin, A. A.; Slyusareva, Ye. D.; Timofeyev, P. V.; Veretenkin, E. P.; Vermul, V. M.; Yantz, V. E.; Zakharov, Yu.; Zatsepin, G. T.; Zhandarov, V. I. [AN SSSR, Mosco

    1990-01-01

    A gallium solar neutrino detector is sensitive to the full range of the solar neutrino spectrum, including the low-energy neutrinos from the fundamental proton-proton fusion reaction. If neutrino oscillations in the solar interior are responsible for the suppressed {sup 8}B flux measured by the Homestake {sup 37}Cl experiment and the Kamiokande water Cherenkov detector, then a comparison of the gallium, chlorine, and water results may make possible a determination of the neutrino mass difference and mixing angle. A 30-ton gallium detector is currently operating in the Baksan laboratory in the Soviet Union, with a ratio of expected solar signal to measured background (during the first one to two {sup 71}Ge half lives) of approximately one. 28 refs.

  3. Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas

    SciTech Connect

    Gomes, R. B.; Fernandes, H.; Silva, C.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C. [Associacao EURATOM/IST, Centro de Fusao Nuclear, Av. Rovisco Pais, 1049-001 Lisboa, Porugal (Portugal); Sarakovskis, A.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I. [Association EURATOM/University of Latvia, Institute of Solid State Physics, 8 Kengaraga Str., LV-1063 Riga (Latvia)

    2008-04-07

    The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages in the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the interaction of a free flying, fully formed liquid gallium jet with the plasma. The interacting, 2.3 mm diameter, jet is generated by hydrostatic pressure and has a 2.5 m/s flow velocity. The liquid metal injector has been build to allow the positioning of the jet inside the tokamak chamber, within a 13 mm range. This paper presents the first obtained experimental results concerning the liquid gallium jet-plasma interaction. A stable jet has been obtained, which was not noticeably affected by the magnetic field transients. ISTTOK has been successfully operated with the gallium jet without degradation of the discharge or a significant plasma contamination by liquid metal. This observation is supported by spectroscopic measurements showing that gallium radiation is limited to the region around the jet. Furthermore, the power deposited on the jet has been evaluated at different radial locations and the surface temperature increase estimated.

  4. CCMR: Gallium Nitride Nanowire Growth and FET Devices Fabrication

    NSDL National Science Digital Library

    Liu, Alison

    2005-08-17

    Being able to develop a high yield procedure where the nanowire growth can be controlled and repeated is very important for building future nanosystems. One goal of the project was to control the nanowire growth by varying different conditions such as temperature and catalyst size. Growth of gallium nitride nanowires of controlled diameters and predetermined sites has successfully been done using gold as the catalysti, but nickel nanoparticles are more difficult to use. Because of its direct band gap semiconductor properties, gallium nitride nanowires are very useful for making electronic and optical nanodevices including field-effect transistor (FET) devices. The second goal of the project was to fabricate such devices.

  5. First results from the Soviet-American Gallium Experiment

    SciTech Connect

    Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.L.; Eroshkina, L.A.; Faizov, E.L.; Gavrin, V.N.; Kalikhov, A.V.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentseva, S.A.; Mirmov, I.N.; Ostrinsky, A.I.; Petukhov, V.V.; Pshukov, A.M.; Revzin, N.Y.; Shikhin, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Zakharov, Y.; Zatsepin, G.T.; Zhandarov, V.I. (AN SSSR, Moscow (USSR). Inst. Yadernykh Issledovanij); Bowl

    1990-01-01

    The Soviet-American Gallium Experiment is the first experiment able to measure the dominant flux of low energy p-p solar neutrinos. Four extractions made during January to May 1990 from 30 tons of gallium have been counted and indicate that the flux is consistent with 0 SNU and is less than 72 SNU (68% CL) and less than 138 SNU (95% CL). This is to be compared with the flux of 132 SNU predicted by the Standard Solar Model. 10 refs., 4 figs., 1 tab.

  6. Mechanism of gallium-67 accumulation in inflammatory lesions

    SciTech Connect

    Tsan, M.F.

    1985-01-01

    Multiple factors contribute to the accumulation and retention of gallium-67 in inflammatory lesions. Adequate blood supply is essential. Gallium-67, mainly in the form of transferrin-Ga-67 complex, is delivered to the inflammatory lesions through capillaries with increased permeability. At the site of inflammation, some Ga-67 is taken up by leukocytes and bacteria when they are present. In addition, Ga-67 may also bind to lactoferrin and bacterial siderophores. Multiple contributing factors often coexist at any given inflammatory lesion. The nature and intensity of the inflammation affects the relative contribution of these factors.

  7. Synthesis and characterization of inorganic-organic hybrid gallium selenides.

    PubMed

    Ewing, Sarah J; Vaqueiro, Paz

    2014-09-01

    Two semiconducting hybrid gallium selenides, [Ga6Se9(C6H14N2)4][H2O] (1) and [C6H14N2][Ga4Se6(C6H14N2)2] (2), were prepared using a solvothermal method in the presence of 1,2-diaminocyclohexane (1,2-DACH). Both materials consist of neutral inorganic layers, in which 1,2-DACH is covalently bonded to gallium. In 1, the organic amine acts as a monodentate and a bidentate ligand, while in 2, bidentate and uncoordinated 1,2-DACH molecules coexist. PMID:25113435

  8. On-chip superconductivity via gallium overdoping of silicon

    NASA Astrophysics Data System (ADS)

    Skrotzki, R.; Fiedler, J.; Herrmannsdörfer, T.; Heera, V.; Voelskow, M.; Mücklich, A.; Schmidt, B.; Skorupa, W.; Gobsch, G.; Helm, M.; Wosnitza, J.

    2010-11-01

    We report on superconducting properties of gallium-enriched silicon layers in commercial (100) oriented silicon wafers. Ion implantation and subsequent rapid thermal annealing have been applied for realizing gallium precipitation beneath a silicon-dioxide cover layer. Depending on the preparation parameters, we observe a sharp drop to zero resistance at 7 K. The critical-field anisotropy proofs the thin-film character of superconductivity. In addition, out-of-plane critical fields of above 9 T and critical current densities exceeding 2 kA/cm2 promote these structures to be possible playgrounds for future microelectronic technology.

  9. Gallium-67 uptake by the thyroid associated with progressive systemic sclerosis

    SciTech Connect

    Sjoberg, R.J.; Blue, P.W.; Kidd, G.S.

    1989-01-01

    Although thyroidal uptake of gallium-67 has been described in several thyroid disorders, gallium-67 scanning is not commonly used in the evaluation of thyroid disease. Thyroidal gallium-67 uptake has been reported to occur frequently with subacute thyroiditis, anaplastic thyroid carcinoma, and thyroid lymphoma, and occasionally with Hashimoto's thyroiditis and follicular thyroid carcinoma. A patient is described with progressive systemic sclerosis who, while being scanned for possible active pulmonary involvement, was found incidentally to have abnormal gallium-67 uptake only in the thyroid gland. Fine needle aspiration cytology of the thyroid revealed Hashimoto's thyroiditis. Although Hashimoto's thyroiditis occurs with increased frequency in patients with progressive systemic sclerosis, thyroidal uptake of gallium-67 associated with progressive systemic sclerosis has not, to our knowledge, been previously described. Since aggressive thyroid malignancies frequently are imaged by gallium-67 scintigraphy, fine needle aspiration cytology of the thyroid often is essential in the evaluation of thyroidal gallium-67 uptake.

  10. Mechanical Alloying

    Microsoft Academic Search

    J. S. Benjamin

    1976-01-01

    A new technique of combining metals has been developed which overcomes many of the limitations of conventional alloying. Ball mills that generate higher energies than conventional ball mills are used to tumble a mixture of powders, such as WC and Co, in order to form a composite. Ni-base alloys can be dispersion-hardened in this way with an oxide such as

  11. Particle dependence of the gallium vacancy production in irradiated n-type gallium arsenide

    SciTech Connect

    Khanna, S.M. [Defence Research Establishment Ottawa, Ontario (Canada)] [Defence Research Establishment Ottawa, Ontario (Canada); Jorio, A.; Carlone, C.; Parenteau, M. [Univ. de Sherbrooke, Quebec (Canada). Dept. de Physique] [Univ. de Sherbrooke, Quebec (Canada). Dept. de Physique; Houdayer, A. [Univ. de Montreal, Quebec (Canada). Dept. de Physique] [Univ. de Montreal, Quebec (Canada). Dept. de Physique; Gerdes, J.W. Jr. [Army Pulse Radiation Facility, Aberdeen Proving Ground, MD (United States)] [Army Pulse Radiation Facility, Aberdeen Proving Ground, MD (United States)

    1995-12-01

    The relative introduction rate of the gallium vacancy in n-type GaAs irradiated with {sup 60}C {gamma} rays, 7 MeV electrons, fusion (14 MeV) and fission (1 MeV) neutrons, protons (0.6 to 200 MeV), deuterons (1 to 10 MeV), {alpha} particles (2.5 to 10 MeV), lithium (5 to 20 MeV) and oxygen ions (10 to 30 MeV) has been determined. Effects of annealing are reported. The measured introduction rates obtained with proton irradiation for energies up to 10 MeV, and for the heavy ions agree reasonably well with Rutherford scattering, NIEL calculations and the TRIM simulation. The results for electron irradiation also agree with the corresponding NIEL calculations.

  12. Proton radiation and thermal stability of gallium nitride and gallium nitride devices

    NASA Astrophysics Data System (ADS)

    Allums, Kimberly K.

    In today's industry one can see a constant challenge to exceed the limits of yesterday's devices. For the last three decades, the III-V nitride semiconductors have been viewed as highly promising for semiconductor device applications. The primary focus of III-V nitrides, thus far, has been centered on light emitting diodes (LEDs), injection lasers for digital data reading and storage applications, and ultra violet photodetectors. Yet, another application is high-power electronic devices for space-borne communications systems. It is expected that GaN-based devices will be more resistant to radiation damage often encountered in space environments, though verification of this is just now being undertaken. In particular, no information is yet available about the sensitivity to radiation of devices using dielectrics such as MOSFETs. Similarly, very limited data has been reported on the effects of high-energy protons on GaN based devices of any type. For this reason the research presented in this dissertation was undertaken to study the radiation and thermal stability of gallium nitride materials and gallium nitride semiconductor diodes, with and without novel gate dielectrics such as, scandium oxide (Sc2O 3) and magnesium oxide (MgO) and the ternary mix of magnesium calcium oxide (MgCaO). It was found that though environmental degradation could be a problem for MgO dielectrics, the radiation exposure itself did not produce significant damage in either the Sc2O3, MgO or MgCaO dielectrics. Much of the minimal damage occurred in the GaN as shown by photoluminescence spectroscopy (PL).

  13. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate

    PubMed Central

    2014-01-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si. PMID:25593562

  14. Corrosion of alloy 718 in a mercury thermal convection loop

    SciTech Connect

    Pawel, S.J.; DiStefano, J.R.; Manneschmidt, E.T.

    1999-12-01

    Two thermal convection loops (TCLs) fabricated from annealed alloy 718 continuously circulated mercury (Hg) with 1000 wppm gallium (Ga), respectively, for about 5000 h, duplicating previous TCL tests for annealed 316L. In each case, the maximum loop temperature was 305C, the minimum temperature was 242C, and the Hg flow rate was approximately 1.2 m/min. Unlike the 316L exposed to Hg, which above about 260C exhibited a thin, porous surface layer depleted in Ni and Cr, the alloy 718 coupons revealed essentially no wetting and, therefore, no interaction with that Hg at any temperature. Alloy 718 coupons suspended in the loops revealed inconsequentially small weight changes, and both the coupons and loop tubing exhibited no detectable metallographic evidence of attack.

  15. Generalized stacking fault energies of alloys.

    PubMed

    Li, Wei; Lu, Song; Hu, Qing-Miao; Kwon, Se Kyun; Johansson, Börje; Vitos, Levente

    2014-07-01

    The generalized stacking fault energy (? surface) provides fundamental physics for understanding the plastic deformation mechanisms. Using the ab initio exact muffin-tin orbitals method in combination with the coherent potential approximation, we calculate the ? surface for the disordered Cu-Al, Cu-Zn, Cu-Ga, Cu-Ni, Pd-Ag and Pd-Au alloys. Studying the effect of segregation of the solute to the stacking fault planes shows that only the local chemical composition affects the ? surface. The calculated alloying trends are discussed using the electronic band structure of the base and distorted alloys.Based on our ? surface results, we demonstrate that the previous revealed 'universal scaling law' between the intrinsic energy barriers (IEBs) is well obeyed in random solid solutions. This greatly simplifies the calculations of the twinning measure parameters or the critical twinning stress. Adopting two twinnability measure parameters derived from the IEBs, we find that in binary Cu alloys, Al, Zn and Ga increase the twinnability, while Ni decreases it. Aluminum and gallium yield similar effects on the twinnability. PMID:24903220

  16. A Review of Liquid Phase Epitaxial Grown Gallium Arsenide

    Microsoft Academic Search

    D. Alexiev; D. A. Prokopovich; S. Thomson; L. Mo; A. B. Rosenfeld; M. Reinhard

    2004-01-01

    Liquid phase epitaxy of gallium arsenide (LPE GaAs) has been investigated intensively from the late 1960's to the present and has now a special place in the manufacture of wide band, compound semiconductor radiation detectors. Although this particular process appears to have gained prominence in the last three decades, it is interesting to note that its origins reach back to

  17. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    E-print Network

    Gross, J L

    2011-01-01

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  18. Abnormal gallium scintigraphy in pulmonary alveolar proteinosis (PAP)

    SciTech Connect

    Yeh, S.D.; White, D.A.; Stover-Pepe, D.E.; Caravelli, J.F.; Van Uitert, C.; Benua, R.S.

    1987-04-01

    A patient with medulloblastoma of the cerebellum developed dyspnea and hypoxemia. Pulmonary function tests showed decreased lung volume and diffusing capacity, while the chest radiographs initially showed only mild interstitial infiltrates. Repeated gallium scans showed diffuse lung uptake and diagnosis of pulmonary alveolar proteinosis was made by open lung biopsy.

  19. Growth and characterization of novel gate dielectrics for gallium nitride

    Microsoft Academic Search

    Andrea H. Onstine

    2004-01-01

    Novel crystalline dielectric materials for gate application on gallium nitride were studied. These dielectric materials must operate at high temperatures and under high power loads. To meet these needs, the selected dielectric materials must be thermally stable to temperatures above 1000°C for device fabrication, must be chemically stable to prevent diffusion into the semiconductor, and must have a low defect

  20. High purity liquid phase epitaxial gallium arsenide nuclear radiation detector

    Microsoft Academic Search

    Dimitri Alexiev; K. S. A. Butcher

    1992-01-01

    Surface barrier radiation detector made from high purity liquid phase epitaxial gallium arsenide wafers have been operated as X- and gamma-ray detectors at various operating temperatures. Low energy isotopes are resolved including 241Am at 40°C and the higher gamma energies of 235U at -80°C.

  1. The 100 micron detector development program. [gallium doped germanium photoconductors

    NASA Technical Reports Server (NTRS)

    Moore, W. J.

    1976-01-01

    An effort to optimize gallium-doped germanium photoconductors (Ge:Ga) for use in space for sensitive detection of far infrared radiation in the 100 micron region is described as well as the development of cryogenic apparatus capable of calibrating detectors under low background conditions.

  2. Improved method of fabricating planar gallium arsenide diodes

    NASA Technical Reports Server (NTRS)

    Roy, M. M.; Yeh, T. H.

    1969-01-01

    Improved method fabricates electroluminescent planar P-N gallium arsenide diodes. GaAs is masked with silicon monoxide to allow P-type impurities to be diffused into unmasked portions of GaAs to form P-N junctions.

  3. GALLIUM--1999 29.1 By Deborah A. Kramer

    E-print Network

    are developing blue and blue-violet LED's based on gallium nitride (GaN). Blue is the last color in the visible and light-emitting diodes (LED's)] as the second largest end use. Several U.S. firms are increasing devices (LED's, laser diodes, photodetectors, and solar cells) and IC's. Analog IC's were the largest end

  4. GALLIUM--1998 29.1 By Deborah A. Kramer

    E-print Network

    . Commercialization of gallium nitride (GaN) laser diodes and LED's is scheduled for 1999. The new GaN devices's manufactured from GaN progressed more rapidly than originally anticipated. Nichia Chemical Industries Inc. of Japan plans to begin commercial shipment of blue GaN laser diodes, which would cost less than $8 each

  5. GALLIUM--1997 29.1 By Deborah A. Kramer

    E-print Network

    gallium nitride (GaN). Laser diodes operate on the same principle as LED's, but they convert electrical their production capabilities. Work is also continuing to commercialize blue light-emitting diodes (LEDAs is manufactured into optoelectronic devices (LED's, laser diodes, photodetectors, and solar cells) and integrated

  6. Accepted Manuscript Title: Isolation and characterization of Gallium resistant

    E-print Network

    Wood, Thomas K.

    of Gallium resistant Pseudomonas aeruginosa mutants, International Journal of Medical Microbiology (2013+ in Pseudomonas aeruginosa mutants Correspondence: Rodolfo García-Contreras, Ph. D. Department of Biochemistry of the phenazine16 pyocyanin biosynthesis. The spontaneous mutant produced 2-fold higher pyocyanin17 basal levels

  7. CCMR: Bulk GaN Growth by Gallium Vapor Transport

    NSDL National Science Digital Library

    Spinelli, Joseph

    2005-08-17

    Gallium nitride (GaN) is currently an extremely popular material used in the fabrication of many optoelectronic and electronic devices such as LEDs and LDs. Since gallium nitride is a direct band gap material there is a much more efficient output of energy. Unlike many other semiconductor materials such as silicon, which will emit a large portion of energy in the form of heat, gallium nitride emits mostly photons. The high electron mobility of the GaN results in the possibility of fabrication high frequency devices, high power devices which can be used for applications such as CD or DVD writing. The influence of high frequency or low wavelength lasers aids in the writing process by allowing more information to be stored in a smaller region of space. However the process required to fabricate high quality GaN crystals is still very costly and slow, thus holding industry back from fabricating mass quantities of GaN commercially. Bulk GaN Growth by Gallium Vapor Transport was attempted

  8. GALLIUM ARSENIDE, INDIUM PHOSPHIDE. CHEMICAL VAPOR DEPOSITION AND PHOTOLUMINESCENCE PROPERTIES

    E-print Network

    Boyer, Edmond

    783 GALLIUM ARSENIDE, INDIUM PHOSPHIDE. CHEMICAL VAPOR DEPOSITION AND PHOTOLUMINESCENCE PROPERTIES manière déséquilibrée. L'intensité de la photo-luminescence dépend distinctement des paramètres the near band gap photoluminescence (PL) of vapor grown layers needs to be improved. Since the luminescence

  9. Magnetorotational Instability in a Short Couette Flow of Liquid Gallium

    Microsoft Academic Search

    Hantao Ji; Jeremy Goodman; Akira Kageyama; Michael Burin; Ethan Schartman; Wei Liu

    2004-01-01

    A concise review is given of an experimental project to study magnetorotational instability (MRI) in a short Couette geometry using liquid gallium. Motivated by the astrophysical importance and lack of direct observation of MRI in nature and in the laboratory, a theoretical stability analysis was performed to predict the required experimental parameters. Despite the long-wavelength nature of MRI, local analysis

  10. Discovery of gallium, germanium, lutetium, and hafnium isotopes

    SciTech Connect

    Gross, J.L.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

    2012-09-15

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  11. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    E-print Network

    J. L. Gross; M. Thoennessen

    2011-09-28

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  12. Self- and zinc diffusion in gallium antimonide

    SciTech Connect

    Nicols, Samuel Piers

    2002-03-26

    The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT) [Dvorak, (2001)]. Many of the findings which will be reported here were previously published in three journal articles. Hartmut Bracht was the lead author on two articles on self-diffusion studies in GaSb [Bracht, (2001), (2000)], while this report's author was the lead author on Zn diffusion results [Nicols, (2001)]. Much of the information contained herein can be found in those articles, but a more detailed treatment is presented here.

  13. Pair distribution function study on compression of liquid gallium

    SciTech Connect

    Luo, Shengnian [Los Alamos National Laboratory; Yu, Tony [SUNY-SB; Chen, Jiuhua [SUNY-SB; Ehm, Lars [SUNY-SB; Guo, Quanzhong [SUNY-SB; Parise, John [SUNY-SB

    2008-01-01

    Integrating a hydrothermal diamond anvil cell (HDAC) and focused high energy x-ray beam from the superconductor wiggler X17 beamline at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL), we have successfully collected high quality total x-ray scattering data of liquid gallium. The experiments were conducted at a pressure range from 0.1GPa up to 2GPa at ambient temperature. For the first time, pair distribution functions (PDF) for liquid gallium at high pressure were derived up to 10 {angstrom}. Liquid gallium structure has been studied by x-ray absorption (Di Cicco & Filipponi, 1993; Wei et al., 2000; Comez et al., 2001), x-ray diffraction studies (Waseda & Suzuki, 1972), and molecular dynamics simulation (Tsay, 1993; Hui et al., 2002). These previous reports have focused on the 1st nearest neighbor structure, which tells us little about the atomic arrangement outside the first shell in non- crystalline materials. This study focuses on the structure of liquid gallium and the atomic structure change due to compression. The PDF results show that the observed atomic distance of the first nearest neighbor at 2.78 {angstrom} (first G(r) peak and its shoulder at the higher Q position) is consistent with previous studies by x-ray absorption (2.76 {angstrom}, Comez et al., 2001). We have also observed that the first nearest neighbor peak position did not change with pressure increasing, while the farther peaks positions in the intermediate distance range decreased with pressure increasing. This leads to a conclusion of the possible existence of 'locally rigid units' in the liquid. With the addition of reverse Monte Carlo modeling, we have observed that the coordination number in the local rigit unit increases with pressure. The bulk modulus of liquid gallium derived from the volume compression curve at ambient temperature (300K) is 12.1(6) GPa.

  14. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (inventor); Starke, Edgar A., Jr. (inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  15. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2005. One company in Utah

    E-print Network

    as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $4 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about was estimated to be 9 metric tons; recycled scrap, 82 metric tons; and imports, 45 metric tons. Included

  16. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2006. One company in Utah

    E-print Network

    as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new $5.5 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented in 2005 to 140 metric tons in 2006. Production was estimated to be 8 metric tons; recycled scrap, 90

  17. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2004. One company in Utah

    E-print Network

    N) electronic components represented about 98% of domestic gallium consumption. About 41% of the gallium 20 20 20 20 20 Net import reliance2 as a percentage of reported consumptione 99 99 99 99 99 Recycling: Old scrap, none. Substantial quantities of new scrap generated in the manufacture of GaAs-base devices

  18. (Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2010. One company in Utah

    E-print Network

    . The rapidly growing high-brightness LED industry was also a significant driver for GaAs- and GaN $35 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about $610 and $650 per kilogram by early October. Market conditions improved significantly for GaAs- and GaN

  19. Photoelectrochemical etching of gallium nitride for high quality optical devices

    NASA Astrophysics Data System (ADS)

    Tamboli, Adele C.

    Gallium nitride has become an important semiconductor material for a variety of device applications, including light emitting diodes (LEDs), lasers, and transistors. One of the main challenges in GaN device fabrication is the chemical stability of GaN which leads to a lack of wet etching techniques. Instead, dry etching is used almost exclusively, leading to ion damage and poor selectivity between different layers. In this dissertation, we discuss photoelectrochemical (PEC) etching, a photoassisted wet etch technique that can be used to etch GaN and its alloys. We develop new aspects of this technique to extend its applicability to a larger variety of devices and use the technique to fabricate a few optical devices, including microdisk lasers. Microdisks are circular resonant cavities that support whispering gallery modes, which propagate around the periphery of the disk, confined by total internal reflection. This geometry has been used to achieve high quality modes, small mode volume, and low threshold lasing in semiconductors such as GaAs and InGaAsP, but has been difficult to fabricate in GaN because it requires a selective wet etch to form undercut, optically isolated cavities. In this dissertation, we discuss the application of PEC etching to the fabrication of GaN microdisks. In our optically pumped, c-plane microdisks, we observe record low threshold lasing under room temperature, continuous-wave operation. In our nonpolar m-plane microdisks, we discovered that the quantum well reabsorption losses that reduce the efficiency of many GaAs and InP microdisks also limit the performance of our nonpolar microdisks, while the piezoelectric fields and corresponding Stokes shift in our c-plane microdisks lead to quantum-dot like behavior and actually lead to superior performance in the polar, c-planemicrodisks. Finally, we report of electrically driven operation of c-plane microdisks for the first time. In these microdisks, first order whispering gallery modes are observed under both optical and electrical injection. We also examine new applications of PEC etching in this dissertation. We have discovered that m-plane GaN, grown homoepitaxially on bulk GaN substrates, etches much more smoothly and predictably than c-plane GaN on sapphire because of the lower defect density and reduced chemical stability of the nonpolar facets. We are able to obtain highly bandgap-selective top-down etching, deep, anisotropic etching, and etches with angled facets. These etch studies open up the possibility of a variety of new m-plane devices fabricated with PEC etching, such as chip-shaped LEDs. We also develop a method for PEC etching of p-type GaN, which has been very difficult to achieve in any semiconductor system. We apply this technique to surface roughening of the p-type, Ga-face side of c-plane LEDs, increasing the light extraction efficiency without the need for flip-chip bonding or substrate removal.

  20. Critical Fields and Growth Rates of the Tayler Instability as Probed by a Columnar Gallium Experiment

    NASA Astrophysics Data System (ADS)

    Rüdiger, Günther; Gellert, Marcus; Schultz, Manfred; Strassmeier, Klaus G.; Stefani, Frank; Gundrum, Thomas; Seilmayer, Martin; Gerbeth, Gunter

    2012-08-01

    Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament, it has been realized in a laboratory experiment measuring the critical field strength, the growth rates, as well as the shape of the supercritical modes. A strong electrical current flows through a liquid metal confined in a resting columnar container with an insulating outer cylinder. As the very small magnetic Prandtl number of the gallium-indium-tin alloy does not influence the critical Hartmann number of the field amplitudes, the electric currents for marginal instability can also be computed with direct numerical simulations. The results of this theoretical concept are confirmed by the experiment. Also the predicted growth rates on the order of minutes for the nonaxisymmetric perturbations are certified by the measurements. That they do not directly depend on the size of the experiment is shown as a consequence of the weakness of the applied fields and the absence of rotation.

  1. Enhanced thermal stability of alpha gallium oxide films supported by aluminum doping

    NASA Astrophysics Data System (ADS)

    Lee, Sam-Dong; Ito, Yoshito; Kaneko, Kentaro; Fujita, Shizuo

    2015-03-01

    In order to enhance the thermal stability of corundum-structured gallium oxide (?-Ga2O3), which is attractive for use in wide-band-gap heterostructure devices and amenable to band gap and function engineering but suffers from phase transformation in high-temperature growth (>500 °C) and treatments (>550 °C), we attempted aluminum (Al) doping. The thermal stability of the films was enhanced by increasing the Al doping concentration, and under the best doping conditions where the Al concentration was negligible compared with the basic chemical composition of Ga2O3, the growth and successive thermal treatment temperatures were increased to as high as 650 and 750 °C, respectively, without the marked appearance of the ?-gallia phase. Under the doping conditions above, the inclusion of Al was not negligible at the growth temperature of 800 °C and the film composition was expressed as an alloy of ?-(Al0.2Ga0.8)2O3, but this film remained as the ?-phase at annealing temperatures up to 900 °C. Enhanced thermal stability widens the device process windows, contributing to the formation of various high-performance devices.

  2. CD71 phenotype and the value of gallium imaging in lymphomas

    SciTech Connect

    Feremans, W.; Bujan, W.; Neve, P.; Delville, J.P.; Schandene, L. (Cliniques Universitaires de Bruxelles, Hopital Erasme (Belgium))

    1991-03-01

    Tumor cells of 14 cases of non-Hodgkin lymphomas and 2 cases of Hodgkin disease were tested for the presence of the transferrin receptor (CD71) by flow cytofluorimetry before 67gallium imaging. It appeared that expression of CD71 phenotype was closely related to the positivity of gallium scan before therapy. We feel that this test is able to predict the avidity for 67gallium and the clinical implications are discussed.

  3. Gallium uptake in the thyroid gland in amiodarone-induced hyperthyroidism

    SciTech Connect

    Ling, M.C.; Dake, M.D.; Okerlund, M.D.

    1988-04-01

    Amiodarone is an iodinated antiarrhythmic agent that is effective in the treatment of atrial and ventricular arrhythmias. A number of side effects are seen, including pulmonary toxicity and thyroid dysfunction. A patient with both amiodarone-induced pneumonitis and hyperthyroidism who exhibited abnormal gallium activity in the lungs, as well as diffuse gallium uptake in the thyroid gland is presented. The latter has not been previously reported and supports the concept of iodide-induced thyroiditis with gallium uptake reflecting the inflammatory response.

  4. Gallium-cooled target for compact accelerator-based neutron sources

    Microsoft Academic Search

    John M. Carpenter

    This paper discusses the motivation for gallium-cooling of targets of compact accelerator-based neutron sources (CANS); summarizes features of the low-power alternative, i.e., water cooling, and the limitations of boiling water heat transfer; lists the properties of liquid gallium; and cites its low hazards potential. I set out working equations for heat transport and fluid flow in liquid gallium and present

  5. Cutaneous gallium uptake in patients with AIDS with mycobacterium avium-intracellulare septicemia

    SciTech Connect

    Allwright, S.J.; Chapman, P.R.; Antico, V.F.; Gruenewald, S.M.

    1988-07-01

    Gallium imaging is increasingly being used for the early detection of complications in patients with AIDS. A 26-year-old homosexual man who was HIV antibody positive underwent gallium imaging for investigation of possible Pneumocystis carinii pneumonia. Widespread cutaneous focal uptake was seen, which was subsequently shown to be due to mycobacterium avium-intracellulare (MAI) septicemia. This case demonstrates the importance of whole body imaging rather than imaging target areas only, the utility of gallium imaging in aiding the early detection of clinically unsuspected disease, and shows a new pattern of gallium uptake in disseminated MAI infection.

  6. Point defect structures in gallium arsenide studied by positron spectroscopies

    NASA Astrophysics Data System (ADS)

    Saarinen, Kimmo

    Positron spectroscopies were used to examine the point defect structure of gallium arsenide. Experiments to investigate the properties of native defects in as-grown GaAs were performed. The defect production during electron irradiation, hydrogen implantation and plastic deformation of GaAs was studied by positron techniques. New information is obtained especially on the properties of vacancy defects. In as-grown GaAs, the ionization levels of arsenic vacancies are determined. In semi-insulation GaAs, the metastable state of the EL2 defect is shown to contain a monovacancy. The introduction of vacancies and antisite defects to the gallium sublattice is observed in electron irradiation of GaAs. In deformed GaAs, the simultaneous formation of vacancies, antisites and vacancy complexes is detected. The depth distributions of vacancies are determined after hydrogen implantation in semi-insulating GaAs, and the recovery of the implantation damage during isochronal annealing is investigated.

  7. Neutron detection using boron gallium nitride semiconductor material

    SciTech Connect

    Atsumi, Katsuhiro [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Inoue, Yoku; Nakano, Takayuki, E-mail: ttnakan@ipc.shizuoka.ac.jp [Department of Electrical and Materials Science, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Mimura, Hidenori; Aoki, Toru [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011 (Japan)

    2014-03-01

    In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN) semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN) samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to ?-rays but poor sensitivity to ?-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after ?-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

  8. Aging and memory effect in magnetoelectric gallium ferrite single crystals

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Mukherjee, Somdutta; Mitra, Chiranjib; Garg, Ashish; Gupta, Rajeev

    2015-02-01

    Here, we present a time and temperature dependent magnetization study to understand the spin dynamics in flux grown single crystals of gallium ferrite (GaFeO3), a known magnetoelectric, ferroelectric and ferrimagnet. Results of the magnetic measurements conducted in the field-cooled (FC) and zero-field-cooled (ZFC) protocols in the heating and cooling cycles were reminiscent of a "memory" effect. Subsequent time dependent magnetic relaxation measurements carried out in ZFC mode at 30 K with an intermittent cooling to 20 K in the presence of a small field show that the magnetization in the final wait period tends to follow its initial state which was present before the cooling break taken at 20 K. These observations provide an unambiguous evidence of single crystal gallium ferrite having a spin glass like phase.

  9. Preparation Of Copper Indium Gallium Diselenide Films For Solar Cells

    DOEpatents

    Bhattacharya, Raghu N. (Littleton, CO); Contreras, Miguel A. (Golden, CO); Keane, James (Lakewood, CO); Tennant, Andrew L. (Denver, CO), Tuttle, John R. (Denver, CO); Ramanathan, Kannan (Lakewood, CO); Noufi, Rommel (Golden, CO)

    1998-08-08

    High quality thin films of copper-indium-gallium-diselenide useful in the production of solar cells are prepared by electrodepositing at least one of the constituent metals onto a glass/Mo substrate, followed by physical vapor deposition of copper and selenium or indium and selenium to adjust the final stoichiometry of the thin film to approximately Cu(In,Ga)Se.sub.2. Using an AC voltage of 1-100 KHz in combination with a DC voltage for electrodeposition improves the morphology and growth rate of the deposited thin film. An electrodeposition solution comprising at least in part an organic solvent may be used in conjunction with an increased cathodic potential to increase the gallium content of the electrodeposited thin film.

  10. Gallium nitride nanowires by maskless hot phosphoric wet etching

    NASA Astrophysics Data System (ADS)

    Bharrat, D.; Hosalli, A. M.; Van Den Broeck, D. M.; Samberg, J. P.; Bedair, S. M.; El-Masry, N. A.

    2013-08-01

    We demonstrate gallium nitride (GaN) nanowires formation by controlling the selective and anisotropic etching of N-polar GaN in hot phosphoric acid. Nanowires of ˜109/cm,2 total height of ˜400 nm, and diameters of 170-200 nm were obtained. These nanowires have both non-polar {11¯00}/ {112¯0} and semi-polar {1011¯} facets. X-Ray Diffraction characterization shows that screw dislocations are primarily responsible for preferential etching to create nanowires. Indium gallium nitride multi-quantum wells (MQWs) grown on these GaN nanowires showed a blue shift in peak emission wavelength of photoluminescence spectra, and full width at half maximum decreased relative to MQWs grown on planar N-polar GaN, respectively.

  11. Dependence of shape memory properties on changes in crystallography in Ni(Mn,Ga) alloys

    NASA Astrophysics Data System (ADS)

    Johnson, Michael Lynn

    Based on previous research at Michigan Technological University, a family of Ni(Mn,Ga) alloys with gallium ranging from 0-25 atomic percent have been studied as examples of variable transformation temperature shape memory alloys. The focus of this work has been to link changes in the crystallography of the martensite to the shape memory behavior of these alloys. Two primary shape memory properties have been examined: transformation behavior using differential scanning caloriometry and mechanical behavior in compression. It has been found that increases in gallium decrease the transformation temperature and improve shape recovery. The decrease in temperature is linked to the increased stability of the austenite phase, while the improved shape recovery can be explained by an increased twin boundary mobility and the suppression of dislocation slip caused by the onset of Heusler ordering. The results show clearly that the transformation temperature and shape recovery behavior can be manipulated by selective alloying to alter the crystallography. These observations are important to the quest for higher transition temperature shape memory alloys.

  12. Use of Gallium-67 in the diagnosis of occult infections

    SciTech Connect

    Hoffer, P.B.

    1981-05-01

    The mechanism of Ga-67 citrates in the diagnosis of infection involves the rapid binding of gallium by transferrin. The Ga-67-transferrin complex gains access into inflammatory tissue to some extent through the leaky endothelium of vessels at sites of inflammation. In addition, Ga-67 binds to a limited extent to circulating neutrophils. Advances in imaging techniques using Ga-67 citrates are discussed. The clinical applications include the diagnosis of bone and joint infections, pulmonary lesions, and infections of the urinary tract.

  13. Optimization stability of gate dielectrics on gallium nitride

    Microsoft Academic Search

    Mark Steven Hlad

    2007-01-01

    The application of gallium nitride (GaN)-based devices requires the use of a gate dielectric to reduce gate leakage, passivate surface traps, and provide isolation between devices. It is critical for the insulator to remain chemically and thermally stable at high temperatures (i.e., 1000°C) during device fabrication and operation. More importantly, it must possess good electrical characteristics such as a high

  14. Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet

    NASA Astrophysics Data System (ADS)

    Gorelov, S. D.; Mashkovich, E. A.; Tsarev, M. V.; Bakunov, M. I.

    2013-12-01

    We report an experimental observation of terahertz Cherenkov radiation from a moving magnetic moment produced in terbium gallium garnet by a circularly polarized femtosecond laser pulse via the inverse Faraday effect. Contrary to some existing theoretical predictions, the polarity of the observed radiation unambiguously demonstrates the paramagnetic, rather than diamagnetic, nature of the ultrafast inverse Faraday effect. From measurements of the radiation field, the Verdet constant in the subpicosecond regime is ˜3-10 times smaller than its table quasistatic value.

  15. Diagnosis of mycotic abdominal aortic aneurysm using 67-gallium citrate

    SciTech Connect

    Blumoff, R.L.; McCartney, W.; Jaques, P.; Johnson, G. Jr.

    1982-11-01

    Mycotic aneurysms of the abdominal aorta are uncommon, but potentially lethal problems. Clinical subtleties may suggest their presence, but in the past, definitive diagnosis has been dependent on surgical exploration or autopsy findings. A case is presented in which 67-gallium citrate abdominal scanning localized the site of sepsis in an abdominal aortic aneurysm and allowed for prompt and successful surgical therapy. This noninvasive technique is recommended as a adjunct in the diagnosis of mycotic abdominal aortic aneurysms.

  16. Copper Indium Gallium Selenide photovoltaic modules manufactured by reactive transfer

    Microsoft Academic Search

    Dingyuan Lu; Baosheng Sang; Yuepeng Deng; B. J. Stanbery; L. Eldada

    2010-01-01

    In recent years, thin-film photovoltaic companies, especially First Solar with its CdTe technology, managed to realize the low manufacturing cost potential and to grab an increasingly larger market share. Copper Indium Gallium Selenide is the most promising thin-film PV material, having demonstrated the highest energy conversion efficiency in both cells and modules. However, most CIGS manufacturers still face the challenge

  17. Gallium67 citrate imaging in underground coal miners

    Microsoft Academic Search

    Richard E. Kanner; H. William Barkman; William N. Rom; Andrew T. Taylor

    1985-01-01

    Twenty-two underground coal workers with 27 or more years of coal dust exposure were studied with gallium-67 citrate (Ga-67) imaging. Radiographic evidence of coal workers indicates that pneumoconiosis (CWP) was present in 12 subjects. The Ga-67 scan was abnormal in 11 of 12 with, and 9 of 10 without, CWP. The Ga-67 uptake index was significantly correlated with total dust

  18. Indium, tin, and gallium doped cadmium selenide quantum dots

    NASA Astrophysics Data System (ADS)

    Tuinenga, Christopher J.

    Doping quantum dots to increase conductivity is a crucial step towards being able to fabricate a new generation of electronic devices built on the "bottom-up" platform that are smaller and more efficient than currently available. Indium, tin, and gallium have been used to dope CdSe in both the bulk and thin film regimes and introduce n-type electron donation to the conduction band. CdSe quantum dots have been successfully doped with indium, tin, and gallium using the Li4[Cd10Se4 (SPh16)] single source precursor combined with metal chloride compounds. Doping CdSe quantum dots is shown to effect particle growth dynamics in the "heterogeneous growth regime." Doping with indium, tin, and gallium introduce donor levels 280, 100, and 50 meV below the conduction band minimum, respectively. Thin films of indium and tin doped quantum dots show improved conductivity over films of undoped quantum dots. Transient Absorption spectroscopy indicates that indium doping introduces a new electron energy level in the conduction band that results in a 70 meV blue shift in the 1Se absorption bleach position. Novel characterization methods such as in-situ fluorescence growth monitoring, single quantum dot EDS acquisition, static and time-resolved temperature dependant fluorescence spectroscopy were developed in the course of this work as well. These results show that doping CdSe quantum dots with indium, tin, and gallium has not only been successful but has introduced new electronic properties to the quantum dots that make them superior to traditional CdSe quantum dots.

  19. Thin-film gallium arsenide homojunction solar cells

    NASA Astrophysics Data System (ADS)

    Chu, S. S.; Chu, T. L.; Zhang, F. S.; Book, L.; Yu, J. M.

    1981-11-01

    Thin film homojunction GaAs solar cells of p(+)/n/n(+) configuration were deposited on tungsten-coated graphic substrates by the reaction of gallium, hydrogen chloride, and arsine containing approriate dopants. Solar cells with an area of 8 cm sq and an AM1 efficiency of about 7% were produced. The observed low fill factor is caused by grain boundary shunting and high series resistance. The cells are characterized by dark and illuminated current voltage and quantum efficiency measurements.

  20. Atomic Mass and Nuclear Binding Energy for Ga-60 (Gallium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume A `Nuclei with Z = 1 - 54' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Ga-60 (Gallium, atomic number Z = 31, mass number A = 60).

  1. Smooth cubic commensurate oxides on gallium nitride

    SciTech Connect

    Paisley, Elizabeth A.; Gaddy, Benjamin E.; LeBeau, James M.; Shelton, Christopher T.; Losego, Mark D.; Mita, Seiji; Collazo, Ramón; Sitar, Zlatko; Irving, Douglas L.; Maria, Jon-Paul, E-mail: jpmaria@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Biegalski, Michael D.; Christen, Hans M. [Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-02-14

    Smooth, commensurate alloys of ?111?-oriented Mg{sub 0.52}Ca{sub 0.48}O (MCO) thin films are demonstrated on Ga-polar, c+ [0001]-oriented GaN by surfactant-assisted molecular beam epitaxy and pulsed laser deposition. These are unique examples of coherent cubic oxide|nitride interfaces with structural and morphological perfection. Metal-insulator-semiconductor capacitor structures were fabricated on n-type GaN. A comparison of leakage current density for conventional and surfactant-assisted growth reveals a nearly 100× reduction in leakage current density for the surfactant-assisted samples. HAADF-STEM images of the MCO|GaN interface show commensurate alignment of atomic planes with minimal defects due to lattice mismatch. STEM and DFT calculations show that GaN c/2 steps create incoherent boundaries in MCO over layers which manifest as two in-plane rotations and determine consequently the density of structural defects in otherwise coherent MCO. This new understanding of interfacial steps between HCP and FCC crystals identifies the steps needed to create globally defect-free heterostructures.

  2. Elevated temperature aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, Peter (Inventor); Lederich, Richard J. (Inventor); O'Neal, James E. (Inventor)

    1989-01-01

    Three aluminum-lithium alloys are provided for high performance aircraft structures and engines. All three alloys contain 3 wt % copper, 2 wt % lithium, 1 wt % magnesium, and 0.2 wt % zirconium. Alloy 1 has no further alloying elements. Alloy 2 has the addition of 1 wt % iron and 1 wt % nickel. Alloy 3 has the addition of 1.6 wt % chromium to the shared alloy composition of the three alloys. The balance of the three alloys, except for incidentql impurities, is aluminum. These alloys have low densities and improved strengths at temperatures up to 260.degree. C. for long periods of time.

  3. Evaluation of the male reproductive toxicity of gallium arsenide.

    PubMed

    Bomhard, Ernst M; Cohen, Samuel M; Gelbke, Heinz-Peter; Williams, Gary M

    2012-10-01

    Gallium arsenide is an important semiconductor material marketed in the shape of wafers and thus is not hazardous to the end user. Exposure to GaAs particles may, however, occur during manufacture and processing. Potential hazards require evaluation. In 14-week inhalation studies with small GaAs particles, testicular effects have been reported in rats and mice. These effects occurred only in animals whose lungs showed marked inflammation and also had hematologic changes indicating anemia and hemolysis. The time- and concentration-dependent progressive nature of the lung and blood effects together with bioavailability data on gallium and arsenic lead us to conclude that the testicular/sperm effects are secondary to hypoxemia resulting from lung damage rather than due to a direct chemical effect of gallium or arsenide. Conditions leading to such primary effects are not expected to occur in humans at production and processing sites. This has to be taken into consideration for any classification decision for reproductive toxicity; especially a category 1 according to the EU CLP system is not warranted. PMID:22728686

  4. Incidental diagnosis of pregnancy on bone and gallium scintigraphy

    SciTech Connect

    Palestro, C.J.; Malat, J.; Collica, C.J.; Richman, A.H.

    1986-03-01

    Bone and gallium scintigraphy were performed as part of the diagnostic workup of a 21-yr-old woman who presented at our institution with a history of progressively worsening low back pain over a 1-wk period of time. The angiographic phase of the bone scan demonstrated a well-defined radionuclide blush within the pelvis just cephalad to the urinary bladder with persistent hyperemia noted in the blood-pool image. We attribute these findings to a uterine blush secondary to the pronounced uterine muscular hyperplasia, hyperemia, and edema that accompany pregnancy. Gallium scintigraphy demonstrated intense bilateral breast accumulation of the imaging agent in a typical doughnut pattern which is commonly found in the prelactating and lactating breast. Also demonstrated was apparent gallium accumulation in the placenta. This case is presented to emphasize the radionuclide findings that occur during pregnancy, particularly the incidental finding of radionuclide blush during the angiographic phase of a radionuclide scintigraphy which should alert the nuclear physician to the possibility of pregnancy in a woman of childbearing age.

  5. Appraisal of lupus nephritis by renal imaging with gallium-67

    SciTech Connect

    Bakir, A.A.; Lopez-Majano, V.; Hryhorczuk, D.O.; Rhee, H.L.; Dunea, G.

    1985-08-01

    To assess the activity of lupus nephritis, 43 patients with systemic lupus erythematosus (SLE) were studied by gallium imaging. Delayed renal visualization 48 hours after the gallium injection, a positive result, was noted in 25 of 48 scans. Active renal disease was defined by the presence of hematuria, pyuria (10 or more red blood cells or white blood cells per high-power field), proteinuria (1 g or more per 24 hours), a rising serum creatinine level, or a recent biopsy specimen showing proliferative and/or necrotizing lesions involving more than 20 percent of glomeruli. Renal disease was active in 18 instances, inactive in 23, and undetermined in seven (a total of 48 scans). Sixteen of the 18 scans (89 percent) in patients with active renal disease showed positive findings, as compared with only four of 23 scans (17 percent) in patients with inactive renal disease (p less than 0.001). Patients with positive scanning results had a higher rate of hypertension (p = 0.02), nephrotic proteinuria (p = 0.01), and progressive renal failure (p = 0.02). Mild mesangial nephritis (World Health Organization classes I and II) was noted only in the patients with negative scanning results (p = 0.02) who, however, showed a higher incidence of severe extrarenal SLE (p = 0.04). It is concluded that gallium imaging is a useful tool in evaluating the activity of lupus nephritis.

  6. Tin-related double acceptors in gallium selenide single crystals

    NASA Astrophysics Data System (ADS)

    Sánchez-Royo, J. F.; Errandonea, D.; Segura, A.; Roa, L.; Chevy, A.

    1998-05-01

    Gallium selenide single crystals doped with different amounts of tin are studied through resistivity and Hall effect measurements in the temperature range from 30 to 700 K. At low doping concentration tin is shown to behave as a double acceptor impurity in gallium selenide with ionization energies of 155 and 310 meV. At higher doping concentration tin also introduces deep donor levels, but the material remains p-type in the whole studied range of tin doping concentrations. The deep character of donors in gallium selenide is discussed by comparison of its conduction band structure to that of indium selenide under pressure. The double acceptor center is proposed to be a tin atom in interlayer position, with a local configuration that is similar to that of tin diselenide. The hole mobility exhibits an anomalous dependence on the tin content, attaining its maximum value in the ingot with 0.2% nominal tin content. This is proposed to be related to impurity pairing effects giving rise to thermal shallow acceptors with low ionization energy and low carrier scattering cross section, making the hole mobility to be controlled by phonon scattering mechanisms even for relatively high impurity content.

  7. POLLUTION PREVENTION IN THE SEMICONDUCTOR INDUSTRY THROUGH RECOVERY AND RECYCLING OF GALLIUM AND ARSENIC FROM GAAS POLISHING WASTES

    EPA Science Inventory

    A process was developed for the recovery of both arsenic and gallium from gallium arsenide polishing wastes. The economics associated with the current disposal techniques utilizing ferric hydroxide precipitation dictate that sequential recovery of toxic arsenic and valuble galliu...

  8. VAl Alloy

    NASA Astrophysics Data System (ADS)

    Mikami, M.; Mizoshiri, M.; Ozaki, K.; Takazawa, H.; Yamamoto, A.; Terazawa, Y.; Takeuchi, T.

    2014-06-01

    Power generation performance of a thermoelectric module consisting of the Heusler Fe2VAl alloy was evaluated. For construction of the module, W-doped Fe2VAl alloys were prepared using powder metallurgy process. Power generation tests of the module consisting of 18 pairs of p- n junctions were conducted on a heat source of 373-673 K in vacuum. The reduction of thermal conductivity and improvement of thermoelectric figure of merit by W-doping enhanced the conversion efficiency and the output power. High output power density of 0.7 W/cm2 was obtained by virtue of the high thermoelectric power factor of the Heusler alloy. The module exhibited good durability, and the relatively high output power was maintained after temperature cycling test in air.

  9. Fabrication, performance and degradation mechanism of aluminum gallium nitride\\/gallium nitride heterostructure field-effect transistors

    Microsoft Academic Search

    Hyungtak Kim

    2003-01-01

    Gallium nitride (GaN) has attracted a lot of attention as the next generation of semiconductor material for microwave power application. The unique and superior material properties of GaN and its heterostructure, such as excellent transport property, high breakdown voltage and sheet carrier concentration, and thermal and mechanical stabilities, enable AlGaN\\/GaN heterostructure field effect transistors (HFETs) to deliver unprecedented levels of

  10. Journal of Crystal Growth 310 (2008) 579583 Red shift in the photoluminescence of indium gallium arsenide nitride

    E-print Network

    Hicks, Robert F.

    2008-01-01

    Journal of Crystal Growth 310 (2008) 579­583 Red shift in the photoluminescence of indium gallium.M. Biefeld Available online 22 November 2007 Abstract The effect of annealing a 75nm-thick layer of indium-phase epitaxy; B1. Nitrogen trifluoride; B2. Indium gallium arsenide nitride 1. Introduction Indium gallium

  11. Chemical vapor deposition of aluminum and gallium nitride thin films from metalorganic precursors

    E-print Network

    Economou, Demetre J.

    Chemical vapor deposition of aluminum and gallium nitride thin films from metalorganic precursors Nearly stoichiometric aluminum and gallium nitride thin films were prepared from hexakis dimethylamido. The barrier properties of the aluminum nitride films in a Si/AlN/Au metallization scheme were examined

  12. Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics

    E-print Network

    Zheludev, Nikolay

    Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics A. V penetration of gallium into an aluminum film. These composite films form mirrorlike interfaces with silica optics and active plasmonics. The material is a polycrystalline aluminum film on a silica sub- strate

  13. Gallium and Indium Complexes for Ring-Opening Polymerization of Cyclic Ethers, Esters and Carbonates

    E-print Network

    Paris-Sud XI, Université de

    1 Gallium and Indium Complexes for Ring-Opening Polymerization of Cyclic Ethers, Esters for the ROP of cyclic ethers 2.2. Gallium complexes for the ROP of cyclic esters and carbonates 3. Indium-based Initiators/catalysts for ROP of cyclic esters 3.1. Synthesis of well-defined indium-based complexes for ROP

  14. Professor Mathias Schubert explains his study of indium gallium nitride semiconductor systems, which

    E-print Network

    Farritor, Shane

    Professor Mathias Schubert explains his study of indium gallium nitride semiconductor systems to your study? Indium gallium nitride (InGaN) could be immediately employed for realising of a new in Indium-rich InGaN. Such conductivity is required for junction-based devices, where the majority current

  15. GALLIUM--2002 29.1 References that include a section mark () are found in the Internet

    E-print Network

    facilities during 2002. Gallium nitride (GaN) continued to be the focus of research and development activities, particularly on methods to improve its properties and to grow bulk GaN. More than 95% of gallium (LEDs, laser diodes, photodetectors, and solar cells) and ICs. Analog ICs were the largest end- use

  16. Low temperature recombination and trapping analysis in high purity gallium arsenide by microwave photodielectric techniques

    NASA Technical Reports Server (NTRS)

    Khambaty, M. B.; Hartwig, W. H.

    1972-01-01

    Some physical theories pertinent to the measurement properties of gallium arsenide are presented and experimental data are analyzed. A model for explaining recombination and trapping high purity gallium arsenide, valid below 77 K is assembled from points made at various places and an appraisal is given of photodielectric techniques for material property studies.

  17. Synthesis and use of (polyfluoroaryl)fluoroanions of aluminum, gallium and indium

    DOEpatents

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

    2000-01-01

    Salts of (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are described. The (polyfluoroaryl)fluoroanions have the formula [ER'R"R'"F].sup..crclbar. wherein E is aluminum, gallium, or indium, wherein F is fluorine, and wherein R', R", and R'" is each a fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic group.

  18. Two-photon photovoltaic effect in gallium arsenide Jeff Chiles,1

    E-print Network

    Fathpour, Sasan

    -photon) photovoltaic effect widely used in solar cells. One possible application of the TPPV effect is selfTwo-photon photovoltaic effect in gallium arsenide Jichi Ma,1 Jeff Chiles,1 Yagya D. Sharma,2 214669); published September 4, 2014 The two-photon photovoltaic effect is demonstrated in gallium

  19. IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption

    E-print Network

    Grandidier, Jonathan

    IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption flat gallium arsenide solar cell, we show that it is possible to modify the flow of light and enhance above the solar cell. The incoupling element is lossless and, thus, has the advantage that no energy

  20. Unexpected gallium uptake in benign pulmonary pathology. Report of two cases

    SciTech Connect

    McLean, R.G.; Choy, D.; Murray, I.P.

    1984-12-01

    Two cases in which pulmonary gallium uptake was demonstrated in benign conditions are reported. In one, the abnormality permitted localization of a benign mesothelioma, while in the other patient it was associated with pulmonary fibrosis resulting from therapeutic irradiation. These cases extend the causes of gallium accumulation in which neither malignancy nor infection is responsible.

  1. Femtosecond laser ablation of gallium arsenide investigated with time-of-flight mass spectroscopy

    E-print Network

    von der Linde, D.

    Femtosecond laser ablation of gallium arsenide investigated with time- of-flight mass spectroscopy laser-induced ablation of gallium arsenide using time-of-flight mass spectroscopy. At the ablation solids laser ablation is not fully understood. In the case of metals and strongly absorbing

  2. Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method

    SciTech Connect

    Budenkova, O. N., E-mail: olganb@mail.ioffe.ru; Vasiliev, M. G.; Yuferev, V. S. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Ivanov, I. A.; Bul'kanov, A. M. [ZAO Research Institute of Materials Science (Russian Federation); Kalaev, V. V. [OOO Soft Impakt (Russian Federation)

    2008-12-15

    Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

  3. A study of surface tension driven segregation in monotectic alloy systems

    NASA Technical Reports Server (NTRS)

    Andrews, J. Barry; Andrews, Rosalia N.; Gowens, Terrell F.

    1988-01-01

    The compatibilities of various monotectic alloy systems with several different crucible materials were evaluated. The study was carried out using small candidate alloy samples of compositions that produced fifty volume percent of each liquid phase at the monotectic temperature. Compatibility was based on the evaluation of the wetting tendency of the two immiscible phases with the crucible material in a one-g solidified sample. Three types of wetting phenomena were observed during the evaluation. Type 1 indicates an alloy-crucible combination where the L2 phase preferentially wets the crucible material. Since L2 is usually the minority phase in desirable alloys, this material combination would be difficult to process and is therefore considered incompatible. Type 2 behavior indicates an alloy-crucible combination where the L1 phase preferentially wets the crucible material. This type of combination is considered compatible since surface tension effects should aid in processing the alloy to a useful form. Type 3 indicates any combination that leads to major reactions between the alloy and crucible material, gas entrapment, or separation of the metal from the crucible wall. Additional compatibility evaluations would have to be carried out on combinations of this category. The five alloy systems studied included aluminum-bismuth, copper-lead, aluminum-indium, aluminum-lead and cadmium-gallium. The systems were combined with crucibles of alumina, boron nitride, mullite, quartz, silicon carbide and zirconia.

  4. Survival of rabbit platelets labeled with gallium 67

    SciTech Connect

    Mazoyer, E.; Carpenter, D.; Ebbe, S.; Yano, Y.; Dalal, K.; Singh, M.; Mazoyer, B.

    1988-02-01

    The viability of rabbit platelets labeled with radioactive gallium was determined to analyze the feasibility of using platelets labeled with gallium 67 as an imaging reagent for positron emission tomography. Platelets were labeled with a complex of the longer lived gallium 67 and mercaptopyridine-N-oxide (MPO) or with sodium chromate Cr 51. Their survival after transfusion was measured. Labelling efficiency of /sup 67/Ga-MPO was 6.5% to 45.8% (26.8% +/- 2.8%) when platelets were suspended in saline solution, but was much lower (1.6% +/- 0.8%) in plasma. Platelets labeled with either radioisotope in a saline medium survived as well as platelets labeled with 51Cr in plasma. Recovery values 1 hour after transfusion and mean platelet survivals were 68.6% +/- 4.9% and 3.4 +/- 0.2 days for /sup 67/Ga in saline solution, 76.5% +/- 6.8% and 3.8 +/- 0.5 days for /sup 51/Cr in saline solution, and 73.7% +/- 7.4% and 3.6 +/- 0.5 days for /sup 51/Cr in plasma. Labeled platelet concentrates always contained extra radioactivity not firmly bound to viable platelets. A postlabeling wash in saline solution did not reduce this contamination and resulted in reduction of the number of viable platelets. The results showed that rabbit platelets labeled with /sup 67/Ga-MPO survived in the circulation as well as those labeled by a standard protocol with sodium chromate Cr 51.

  5. Interdiffusion of magnesium and iron dopants in gallium nitride

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Tomonobu; Kitatani, Takeshi; Terano, Akihisa; Mochizuki, Kazuhiro

    2015-03-01

    The interdiffusion of magnesium and iron in gallium nitride (GaN), i.e., magnesium–iron interdiffusion, was investigated using magnesium-doped GaN layers on iron-doped GaN substrates. The investigation confirms that the magnesium–iron interdiffusion strongly depends on the concentrations of magnesium and iron, that is, it occurs when the iron and magnesium concentrations are high (magnesium: 2 × 1020 cm?3 iron: 2 × 1019 cm?3). It also confirms that diffused iron in the magnesium-doped GaN layer acts as a nonradiative recombination center in GaN.

  6. Spectroscopy of vanadium (III) doped gallium lanthanum sulphide chalcogenide glass

    E-print Network

    Hughes, M; Rutt, H; Hewak, D

    2014-01-01

    Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730 and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width half maximum (FWHM) of 500 nm, is observed peaking at 1500 nm when exciting at 514, 808 and 1064 nm. The fluorescence lifetime and quantum efficiency at 300 K were measured to be 33.4 us and 4 % respectively. From the available spectroscopic data we propose the vanadium ions valence to be 3+ and be in tetrahedral coordination The results indicate potential for development of a laser or optical amplifier based on V:GLS.

  7. Self-diffusion in liquid gallium and hard sphere model

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskii, Nikolay; Novikov, Arkady; Puchkov, Alexander; Savostin, Vadim; Sobolev, Oleg

    2015-01-01

    Incoherent and coherent components of quasielastic neutron scattering have been studied in the temperature range of T = 313 K - 793 K aiming to explore the applicability limits of the hard-sphere approach for the microscopic dynamics of liquid gallium, which is usually considered as a non-hard-sphere system. It was found that the non-hard-sphere effects come into play at the distances shorter than the average interatomic distance. The longer range diffusive dynamics of liquid Ga is dominated by the repulsive forces between the atoms.

  8. Gallium uptake in tryptophan-related pulmonary disease

    SciTech Connect

    Kim, S.M.; Park, C.H.; Intenzo, C.M.; Patel, R. (Thomas Jefferson Univ. Hospital, Philadelphia, PA (USA))

    1991-02-01

    We describe a patient who developed fever, fatigue, muscle weakness, dyspnea, skin rash, and eosinophilia after taking high doses of tryptophan for insomnia for two years. A gallium-67 scan revealed diffuse increased uptake in the lung and no abnormal uptake in the muscular distribution. Bronchoscopy and biopsy confirmed inflammatory reactions with infiltration by eosinophils, mast cells, and lymphocytes. CT scan showed an interstitial alveolar pattern without fibrosis. EMG demonstrated diffuse myopathy. Muscle biopsy from the right thigh showed an inflammatory myositis with eosinophilic and lymphocytic infiltrations.

  9. Testing of gallium arsenide solar cells on the CRRES vehicle

    NASA Astrophysics Data System (ADS)

    Trumble, T. M.

    A flight experiment was designed to determine the optimum design for gallium arsenide (GaAs) solar cell panels in a radiation environment. Elements of the experiment design include, different coverglass material and thicknesses, welded and soldered interconnects, different solar cell efficiencies, different solar cell types, and measurement of annealing properties. This experiment is scheduled to fly on the Combined Release and Radiation Effects Satellite (CRRES). This satellite will simultaneously measure the radiation environment and provide engineering data on solar cell degradation that can be directly related to radiation damage.

  10. Amorphous metal alloys produced by mechanical alloying

    SciTech Connect

    Tiainen, T.J.; Schwarz, R.B.

    1989-01-01

    Mechanical alloying is a powder metallurgy method used in commercial production of high temperature superalloys. Under specific conditions, mechanical alloying allows the synthesis of amorphous metal alloys from mixtures of pure metal powders or from the powders of intermetallic compounds. Because the amorphizing transformation during mechanical alloying is a solid state reaction, most of the difficulties related to the amorphization by rapid solidification of melts can be avoided. Mechanical alloying allows the synthesis of amorphous alloys from metals with high melting temperatures and the resulting alloys have interesting properties such as high hardness and high crystallization temperatures. We used mechanical alloying for the synthesis of amorphous alloys in the binary alloy systems Nl-Sn, Nb-Si and Al-Hf. The amorphous alloy powders were characterized by x-ray diffraction, differential scanning calorimetry, scanning and transmission electron microscopy and hardness measurements. Produced alloys were compacted by hot pressing and the obtained compacts were characterized by x-ray diffraction, density and hardness measurements and by optical and scanning electron microscopy. The results of the amorphization and compaction studies are presented and discussed together with the characteristics of the mechanical alloying process. 15 refs., 5 figs.

  11. Gallium Nitride, Indium Nitride, and Heterostructure Development Using The MEAglow Growth System

    NASA Astrophysics Data System (ADS)

    Binsted, Peter W.

    This thesis presents an in depth study of semiconductor development using a new process termed Migration Enhanced Afterglow (MEAglow). The MEAglow growth reactor is housed in the Lakehead University Semiconductor Research Lab. Thin films of gallium nitride and indium nitride are produced as well as heterostructures comprised of these two films and their ternary alloy InGaN. MEAglow is a form of plasma enhanced chemical vapour deposition (PECVD) employing migration enhanced epitaxy (MEE). The heterostructure is being developed for a novel field effect transistor (FET) based on the tunnelling of charge carriers which alter the channel conductivity. The configuration of this unique III-Nitride device should allow the FET to function as normally off in either n-type or p-type operation. Due to the difficulties in growing low temperature GaN, test devices of this abstract design were not previously possible. Further details on the device operation and growth parameters are included. Samples produced by the research reactor were characterised through x-ray diffraction (XRD), ultraviolet-near infrared-visible spectroscopy (UV-Vis-NIR), Auger spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Film growth is accomplished by an improved form of pulsed delivery Plasma Enhanced Chemical Vapour Deposition (PECVD). The reactor features a scalable hollow cathode type plasma source. Data obtained through characterisation is subjected to theoretical treatment which explains much not previously understood behaviour of the GaN films. Many challenges in III-Nitride film growth have been overcome during this research project. A method of developing structures consisting of InN and GaN within the same system has been proven.

  12. Growth and characterization of gallium nitride and boron gallium nitride by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wei, Chih-Hsun

    1999-11-01

    The growth of wurtzite GaN epilayers on c-plane sapphire substrates, zinc blende GaN on 3C-SiC/Si(100), and BGaN alloys on 6H-SiC substrates via low-pressure metalorganic chemical vapor deposition (MOCVD) was investigated. The low-temperature nucleation layer plays a significant role in the growth of high-quality GaN films; consequently, the effect of trimethylgallium flow during the buffer layer growth on the properties of high-temperature GaN epilayer was studied. An optimal TMG flow reduced the three-dimensional island growth mode of the nucleation layer and improved the crystalline quality and electrical properties of the GaN epilayer. Zinc blende GAN films were grown on Si(100) substrates with a 3C-SiC intermediate layer by MOCVD. The nucleation of the zinc blende phase and its subsequent growth depend on three key factors: a smooth SiC layer, a high growth temperature, and a moderate V/III ratio. A GaN layer with cubic content of 91% was obtained under optimal growth conditions. For BxGa1-xN alloy growth, thermodynamic analysis determined the conditions for its deposition and predicted the equilibrium partial pressure of the gaseous species, vapor- solid distribution relationship, and growth efficiency. The activities of BN and GaN were calculated from the interaction parameter of BN-GaN using the delta-lattice-parameter (DLP) method. Due to the large structural dissimilarity between BN and GaN, BGaN alloys are very unstable and prone to phase separation. The influence of the B/Ga gas ratio on the structural, phases, growth rate, and energy bandgap of BGaN films deposited on 6H-SiC (0001) substrates at 1000°C and 76 torr was systematically investigated. A single-phase, single-crystal BxGa 1-xN alloy with x = 1.5% was successfully grown at B/Ga = 0.005. For B/Ga ratio in the 0.01--0.02 range, the solid solution decomposed into the wurtzite BGaN and B-rich phase. A small amount of boron incorporation decreased the FWHM of PL indicating an improvement of the quality of the GaN epilayer. Finally, the unstable composition region of B1-x-y GaxAlyN was calculated from the free energy of mixing based on the strictly regular solution model. The high interaction parameters of BN-GaN and BN-AlN seriously limit the growth of uniform single-crystals of these solid solutions and result in very wide unstable composition regions.

  13. Technetium-99m DTPA aerosol and gallium scanning in acquired immune deficiency syndrome

    SciTech Connect

    Picard, C.; Meignan, M.; Rosso, J.; Cinotti, L.; Mayaud, C.; Revuz, J.

    1987-07-01

    In 11 non-smoking AIDS patients suspected of pneumocystis carinii pneumonia (PCP), the results of Tc-99m DTPA aerosol clearances, gallium scans, and arterial blood gases were compared with those of bronchoalveolar lavage (BAL). Nine patients had PCP. All had increased clearances five times higher than the normal (5.6 +/- 2.3% X min-1 vs 1.1 +/- 0.34% X min-1, N = 10, P less than 0.001), suggesting an increased alveolar permeability. Gallium scans were abnormal in six patients but normal or slightly abnormal in the three others. Four of these nine patients had normal chest x-rays. In two of these the gallium scan was abnormal, but in the two others, only the increased Tc-99m DTPA clearances showed evidence of lung disease. Two patients had normal BAL, with normal clearances and gallium scans. Four out of the nine patients with PCP were studied after treatment. Three recovered and had normal clearance and gallium scans. One still had PCP with increased clearance but normal gallium scan. Gallium scanning and Tc-99m DTPA clearance are useful for detecting lung disease in AIDS patients with suspected PCP and for prompting BAL when chest x-rays and PaO/sub 2/ levels are normal. Due to its high sensitivity, a normal Tc-99m DTPA clearance could avoid BAL.

  14. Study on natural convection capability of liquid gallium for passive decay heat removal system (PDHRS)

    SciTech Connect

    Kang, S. [Ulsan National Inst. of Science and Technology UNIST, 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulasn Metropolitan City 689-798 (Korea, Republic of); Ha, K. S. [Korea Atomic Energy Research Inst. KAERI, Deokjin-dong, Yuseong-gu, Daejeon, 305-600 (Korea, Republic of); Lee, S. W.; Park, S. D.; Kim, S. M.; Seo, H.; Kim, J. H.; Bang, I. C. [Ulsan National Inst. of Science and Technology UNIST, 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulasn Metropolitan City 689-798 (Korea, Republic of)

    2012-07-01

    The safety issues of the SFRs are important due to the fact that it uses sodium as a nuclear coolant, reacting vigorously with water and air. For that reason, there are efforts to seek for alternative candidates of liquid metal coolants having excellent heat transfer property and to adopt improved safety features to the SFR concepts. This study considers gallium as alternative liquid metal coolant applicable to safety features in terms of chemical activity issue of the sodium and aims to experimentally investigate the natural convection capability of gallium as a feasibility study for the development of gallium-based passive safety features in SFRs. In this paper, the design and construction of the liquid gallium natural convection loop were carried out. The experimental results of heat transfer coefficient of liquid gallium resulting in heat removal {approx}2.53 kW were compared with existing correlations and they were much lower than the correlations. To comparison of the experimental data with computer code analysis, gallium property code was developed for employing MARS-LMR (Korea version of RELAP) based on liquid gallium as working fluid. (authors)

  15. Low temperature solid-state synthesis of nanocrystalline gallium nitride

    SciTech Connect

    Wang, Liangbiao, E-mail: wlb6641@163.com [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Liang; Li, Qianwen; Si, Lulu; Zhu, Yongchun; Qian, Yitai [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ? GaN nanocrystalline was prepared via a solid-state reacion at relatively low temperature. ? The sizes and crystallinities of the GaN samples obtained at the different temperatures are investigated. ? The GaN sample has oxidation resistance and good thermal stability below 1000 °C. -- Abstract: Nanocrystalline gallium nitride was synthesized by a solid-state reaction of metallic magnesium powder, gallium sesquioxide and sodium amide in a stainless steel autoclave at a relatively low temperature (400–550 °C). The structures and morphologies of the obtained products were derived from X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). XRD patterns indicated that the products were hexagonal GaN (JCPDS card no. 76-0703). The influence of reaction temperature on size of the products was studied by XRD and TEM. Furthermore, the thermal stability and oxidation resistance of the nanocrystalline GaN were also investigated. It had good thermal stability and oxidation resistance below 800 °C in air.

  16. Gadolinium Gallium Garnet at Multi-Megabar Pressures

    NASA Astrophysics Data System (ADS)

    Millot, M.; Ali, S. J.; Militzer, B.; Barrios, M. A.; Boehly, T.; Eggert, J. H.; Collins, G.; Jeanloz, R.

    2011-12-01

    Gadolinium gallium oxide Gd3Ga5O12, which crystallizes in the garnet structure, has recently attracted strong interest due to shock-wave experiments revealing a highly incompressible high-pressure phase above 1 Mbar [1]. In addition, recent diamond-cell x-ray diffraction experiments provide evidence for a phase transition from garnet to double-perovskite structures around 1 Mbar [2]. We present the results of laser-driven shock experiments on gadolinium gallium garnet (GGG) at pressures of 3 to more than 20 Mbar, obtained at the Omega-LLE and Jupiter-LLNL facilities, and compare these with the results of ab-initio molecular dynamic simulations. Velocimetry (VISAR) and pyrometry (SOP) diagnostics, and an impedance match analysis with quartz standards, provide data on the equation of state, temperature and optical reflectivity at 532 nm. No obvious phase transition is detected in the explored pressure range, but the data indicate that GGG remains surprisingly stiff up to more than 20 Mbar. We observe metallic-like reflectivity in the ultra-high pressure (possibly liquid) regime. This study could be relevant for planetary interior modeling, as many Earth and super-Earth minerals adopt the garnet and perovskite structures, and may exhibit transition to metallic and highly incompressible behavior.

  17. Gallium-67 citrate imaging in underground coal miners.

    PubMed

    Kanner, R E; Barkman, H W; Rom, W N; Taylor, A T

    1985-01-01

    Twenty-two underground coal workers with 27 or more years of coal dust exposure were studied with gallium-67 citrate (Ga-67) imaging. Radiographic evidence of coal workers pneumoconiosis (CWP) was present in 12 subjects. The Ga-67 scan was abnormal in 11 of 12 with, and 9 of 10 without, CWP. The Ga-67 uptake index was significantly correlated with total dust exposure (p less than 0.01) and approached significant correlation with the radiographic profusion of the nodules (0.10 greater than p greater than 0.05). There was no correlation between Ga-67 uptake and spirometric function, which was normal in this group of patients; furthermore, increased lung uptake of gallium did not indicate a poor prognosis in subjects no longer exposed to coal dust. While coal dust exposure may be associated with positive Ga-67 lung scan in coal miners with many years of coal dust exposure, the scan provided no information not already available from a careful exposure history and a chest radiograph. Since Ga-67 scanning is a relatively expensive procedure we would recommend that its use in subjects with asymptomatic CWP be limited to an investigative role and not be made part of a routine evaluation. PMID:4025338

  18. Gallium-67 citrate imaging in underground coal miners

    SciTech Connect

    Kanner, R.E.; Barkman, H.W. Jr.; Rom, W.N.; Taylor, A.T. Jr.

    1985-01-01

    Twenty-two underground coal workers with 27 or more years of coal dust exposure were studied with gallium-67 citrate (Ga-67) imaging. Radiographic evidence of coal workers indicates that pneumoconiosis (CWP) was present in 12 subjects. The Ga-67 scan was abnormal in 11 of 12 with, and 9 of 10 without, CWP. The Ga-67 uptake index was significantly correlated with total dust exposure (p less than 0.01) and approached significant correlation with the radiographic profusion of the nodules (0.10 greater than p greater than 0.05). There was no correlation between Ga-67 uptake and spirometric function, which was normal in this group of patients; furthermore, increased lung uptake of gallium did not indicate a poor prognosis in subjects no longer exposed to coal dust. While coal dust exposure may be associated with positive Ga-67 lung scan in coal miners with many years of coal dust exposure, the scan provided no information not already available from a careful exposure history and a chest radiograph. Since Ga-67 scanning is a relatively expensive procedure the authors would recommend that its use in subjects with asymptomatic CWP be limited to an investigative role and not be made part of a routine evaluation.

  19. High-surface Thermally Stable Mesoporous Gallium Phosphates Constituted by Nanoparticles as Primary Building Blocks

    SciTech Connect

    V Parvulescu; V Parvulescu; D Ciuparu; C Hardacre; H Garcia

    2011-12-31

    In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl{sub 3} and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C{sub 16}H{sub 33}(CH{sub 3})3NBr and C{sub 16}PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl{sub 3} and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m{sup 2} g{sup -1}, and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis.

  20. Iron-Targeting Antitumor Activity of Gallium Compounds and Novel Insights Into Triapine®-Metal Complexes

    PubMed Central

    Antholine, William E.

    2013-01-01

    Abstract Significance: Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Recent Advances: Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise for the treatment of cancer. Recent studies show that gallium compounds and metal-thiosemicarbazone complexes inhibit tumor cell growth by targeting iron homeostasis, including iron-dependent ribonucleotide reductase. Chemical similarities of gallium(III) with iron(III) enable the former to mimic the latter and interpose itself in critical iron-dependent steps in cellular proliferation. Newer gallium compounds have emerged with additional mechanisms of action. In clinical trials, the first-generation-compound gallium nitrate has exhibited activity against bladder cancer and non-Hodgkin's lymphoma, while the thiosemicarbazone Triapine® has demonstrated activity against other tumors. Critical Issues: Novel gallium compounds with greater cytotoxicity and a broader spectrum of antineoplastic activity than gallium nitrate should continue to be developed. Future Directions: The antineoplastic activity and toxicity of the existing novel gallium compounds and thiosemicarbazone-metal complexes should be tested in animal tumor models and advanced to Phase I and II clinical trials. Future research should identify biologic markers that predict tumor sensitivity to gallium compounds. This will help direct gallium-based therapy to cancer patients who are most likely to benefit from it. Antioxid. Redox Signal. 00, 000–000. PMID:22900955

  1. A hypothesis for anti-nanobacteria effects of gallium with observations from treating kidney disease.

    PubMed

    Eby, George A

    2008-10-01

    Nanobacteria, 100-fold smaller than common bacteria, have been purported to exist in urine, and by precipitating calcium and other minerals into carbonate apatite around themselves, induce the formation of surrounding kidney stones. Nanobacteria-like structures have also been shown in blood, within arteries, aortic aneurysms, and cardiac valves. Gallium has antibiotic properties to iron-dependent bacteria and has potent anti-inflammatory, anticancer and anti-hypercalcemic properties, and it readily reverses osteoporosis. It was hypothesized that gallium nitrate might have benefit in treating kidney stones. Gallium nitrate (120mg gallium) was mixed with water making two liters of a gallium mineral water drink to treat chronic, treatment-resistant kidney stone pain and urinary tract bleeding in a 110 pound woman. On the third day of gallium mineral water treatment, the urine appeared snow white, thick (rope-like) and suggestive of a calcific crystalline nature. After release of the white urine, the urine returned to normal in color, viscosity and pH, kidney pain was no longer present, and there was no further evidence of blood in the urine. There were no treatment side effects or sequela. For a one year observation period thereafter, no kidney stones, white urine, kidney or urinary tract pain or blood in the urine was noted. The hypothetical susceptibility of nanobacteria to gallium treatment also suggests application to atherosclerosis and other diseases. Although some support for gallium in treating kidney stones is presented, this hypothesis is built upon another hypothesis, is extremely speculative, and alternative explanations for the white urine exist. Further research into gallium's effects on kidney disease and other nanobacteria-induced diseases such as cardiovascular diseases is suggested. PMID:18579317

  2. Structure and phase stability of a Pu-0.42 wt.% Ga alloy

    NASA Astrophysics Data System (ADS)

    Wheeler, D. W.; Ennaceur, S. M.; Matthews, M. B.; Roussel, P.

    2014-09-01

    This paper describes the characterisation of a cast plutonium-gallium (Pu-0.42 wt.% Ga) alloy, both in the as-cast condition as well as following an homogenising heat treatment. The alloy was subjected to density measurements, differential scanning calorimetry (DSC), dilatometry, optical microscopy, electron probe micro-analysis (EPMA), X-ray diffraction (XRD) and hardness measurements. The Ga content is insufficient to retain a wholly delta-Pu (?-Pu) phase in the as-cast condition. However, the 250-h heat treatment at 450 °C is sufficient to redistribute the Ga resulting in an apparently stable ?-Pu phase. DSC and dilatometry did not indicate the presence of any alpha-Pu (?-Pu) phase in the heat-treated alloy. XRD patterns of the alloys also showed ?-Pu to be present, although in the case of the heat-treated alloy this may be a consequence of incomplete removal of the transformed surface layer during the electro-polishing process. The stability of the ?-Pu phase in the heat-treated alloy was evaluated by cooling specimens to sub-zero temperatures. The alloy exhibited a high degree of stability when subjected to cold treatments at temperatures of between -50 °C and -90 °C.

  3. Metal alloy identifier

    DOEpatents

    Riley, William D. (Avondale, MD); Brown, Jr., Robert D. (Avondale, MD)

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  4. Process for producing gallium-containing solution from the aluminum smelting dust

    SciTech Connect

    Era, A.; Matsui, S.; Ikeda, H.

    1988-03-01

    A process is described for producing a gallium-containing solution from aluminum smelting dust comprising leaching aluminum smelting dust with a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid, and adding an oxidizing agent to the aluminum smelting dust at the time of leaching to preferentially leach and extract gallium from the aluminum smelting dust without extracting aluminum from the aluminum smelting dust. The oxidizing agent is selected from the group consisting of potassium permanganate, manganese dioxide, hydrogen peroxide, ozone, potassium chromate, potassium dichromate, ammonium persulfate, sodium hydrochlorite, sodium chlorite and sodium chlorate. The leached aluminum smelting dust is filtered to obtain a gallium-containing solution of dissolved gallium.

  5. Gallium-67 detection of intramammary injection sites secondary to intravenous drug abuse

    SciTech Connect

    Swayne, L.C. (Morristown Memorial Hospital, NJ (USA))

    1989-09-01

    A case of gallium localization within the breast occurred secondary to intravenous drug abuse. In the appropriate clinical setting, prior self-administered injections should be considered as a cause of Ga-67 accumulation at unusual sites.

  6. Resistivity and equation of state of warmed gallium melt in megabar pressure

    NASA Astrophysics Data System (ADS)

    Golyshev, A. A.; Molodets, A. M.

    2014-05-01

    The electrical conductivity of gallium melt was measured under multiple-shock compression up to thickapprox 100 GPa. The semi-empirical equations of state (EOS) are constructed in the shock pressure range 30-300 GPa. The EOS were used for reconstruction of the thermodynamic history of the sample in the experiments and for the subsequent definition of the volume-temperature dependence of gallium melt resistivity. It was shown that the volume-temperature dependence of gallium melt is proportional to temperature and inversely to the square of characteristic temperature in the shock pressure range 30-80 GPa and temperatures of 1000-2000 K. Thus warmed high pressure gallium phase melt possesses metal conductivity.

  7. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    SciTech Connect

    Podhorodecki, A.; Banski, M.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Lecerf, C.; Marie, P.; Cardin, J.; Portier, X. [CIMAP, CEA/UMR CNRS 6252/ENSICAEN, Universite de Caen Basse Normandie, 6 Boulevard Marechal Juin, 14050 Caen (France)

    2010-09-15

    Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  8. GALLIUM--2003 28.1 References that include a section mark () are found in the Internet

    E-print Network

    . LEDs also have made inroads into mobile applications, such as brake and signal lights on automobiles of digital video disk (DVD) recorders with GaN laser diodes. More than 95% of the gallium consumed

  9. Polycrystalline Thin-Film Research: Copper Indium Gallium Diselenide (Fact Sheet)

    SciTech Connect

    Not Available

    2011-06-01

    Capabilities fact sheet for the National Center for Photovoltaics: Polycrystalline Thin-Film Research: Copper Indium Gallium Diselenide that includes scope, core competencies and capabilities, and contact/web information.

  10. Luminescence dynamics and waveguide applications of europium doped gallium nitride powder

    E-print Network

    Lipson, Michal

    Luminescence dynamics and waveguide applications of europium doped gallium nitride powder Carl B, bismuth shot, and europium ingot in an ammonia ambient to initially obtain chunks of the desired material

  11. Renal gallium accumulation in the absence of renal pathology in patients with severe hepatocellular disease

    SciTech Connect

    Alazraki, N.; Sterkel, B.; Taylor, A. Jr.

    1983-05-01

    Visualization of Ga-67 citrate in the kidneys at 48 hours and 72 hours post injection is usually interpreted as evidence of renal pathology. In reviewing approximately 200 consecutive patients referred for gallium scans, 40 patients who also underwent liver/spleen Tc-99m sulfur colloid (SC) studies within one month of the gallium study were identified. Fourteen of these patients showed advanced hepatocellular dysfunction on the Tc-99m SC liver/spleen images. Of these 14 patients, nine had persistent renal accumulation of gallium at 48 or 72 hours. Five of these nine patients had no evidence of primary renal disease by clinical or postmortem examination and subsequent clinical information indicated that two additional patients probably had no significant renal pathology. Therefore, bilateral symmetrically increased renal uptake of gallium in patients with advanced hepatocellular disease should not necessarily be interpreted as evidence of renal pathology.

  12. Utility of gallium imaging of the kidneys in diagnosing primary amyloid nephrotic syndrome

    SciTech Connect

    Gertz, M.A.; Brown, M.L.; Hauser, M.F.; Kyle, R.A. (Mayo Clinic, Rochester, MN (USA))

    1990-03-01

    We undertook a study to determine the value of gallium imaging of the kidneys in patients who had primary amyloidosis that was manifest clinically by nephrotic syndrome. We studied 28 patients with gallium-67 (67Ga) citrate scans performed 48 hr after injection. Intense (3+ to 4+) uptake was noted in both kidneys in 25 of 28 patients. Renal amyloidosis should be considered in the differential diagnosis when diffuse bilateral renal uptake of (67Ga)citrate is seen in the setting of nephrotic syndrome. Gallium uptake did not differentiate amyloid nephrotic syndrome from other causes of nephrotic syndrome. Renal gallium uptake showed a weak correlation with 24-hr urine protein excretion (p = 0.06).

  13. Spectroscopic, optical, and thermomechanical properties of neodymium- and chromium-doped gadolinium scandium gallium garnet

    Microsoft Academic Search

    W. F. Krupke; M. D. Shinn; J. E. Marion; J. A. Caird; S. E. Stokowski

    1986-01-01

    Spectroscopic, optical, and thermomechanical properties of gadolinium scandium gallium garnet doped with trivalent neodymium and\\/or chromium are reported for use in the design of high-power solid-state lasers.

  14. Gallium Content in PuO{sub 2} Using Laser Induced Breakdown Spectroscopy (LIBS)

    SciTech Connect

    Smith, C.A.; Martinez, M.A.; Veirs, D.K.

    1999-08-29

    Laser Induced Breakdown Spectroscopy (LIBS) has been applied to the semi-quantitative analysis of gallium in plutonium oxide at the Los Alamos Plutonium Facility. The oxide samples were generated by the Thermally Induced Gallium Removal (TIGR) process, a pretreatment step prior to MOX fuel processing. The TIGR process uses PuO{sub 2} containing 1 wt% gallium (nominal) as feed material. Following the TIGR process, gallium content was analyzed by LIBS and also by conventional wet chemical analysis (ICP-MS). Although the data range was insufficient to obtain an adequate calibration, general agreement between the two techniques was good. LIBS was found to have a useful analytical range of 34-400 ppm for Ga in PuO{sub 2}.

  15. Irradiated solar cells fabricated from gallium-doped/boron-doped FZ and CZ silicon

    SciTech Connect

    Minahan, J.A.; Dionne, N.N.D.; Taylor, W.E.; Trumble, T.M.

    1982-09-01

    The purpose of this study is to compare the tolerance to various fluence levels of 1 MeV electrons of solar cells fabricated from: gallium-doped multipass FZ silicon, boron-doped multipass FZ silicon, gallium doped CZ silicon and boron doped CZ silicon. The FZ materials used for the study were of ultra high purity with low levels of oxygen and carbon. Bulk analysis of gallium doped cold crucible (C/sup 3/Z) silicon is included and compared with gallium doped FZ silicon. Bulk analysis of selected wafers in the various crystals was performed by low temperature FTIR and surface photovoltage. Measurement of AMO electrical characteristics and spectral response of solar cells fabricated from these silicon materials before and after 1 MeV electron irradiation are used to compare radiation tolerance of the materials.

  16. Early supradiaphragmatic Hodgkin's disease. High-dose gallium scanning obviates the need for staging laparotomy

    SciTech Connect

    Blackwell, E.A.; Joshua, D.E.; McLaughlin, A.F.; Green, D.; Kronenberg, H.; May, J.

    1986-08-15

    Experience with 16 sequential patients with Stage IA/IIA supradiaphragmatic Hodgkin's disease who had no evidence of intra-abdominal disease using high-dose gallium and computerized tomography scanning is reported. Subsequent staging laparotomy also was negative in all these patients and did not alter management decisions. It is suggested that high-dose, whole-body gallium scanning and other noninvasive staging procedures give reliable data for therapeutic decisions.

  17. Bit-systolic arithmetic arrays using dynamic differential gallium arsenide circuits

    NASA Technical Reports Server (NTRS)

    Beagles, Grant; Winters, Kel; Eldin, A. G.

    1992-01-01

    A new family of gallium arsenide circuits for fine grained bit-systolic arithmetic arrays is introduced. This scheme combines features of two recent techniques of dynamic gallium arsenide FET logic and differential dynamic single-clock CMOS logic. The resulting circuits are fast and compact, with tightly constrained series FET propagation paths, low fanout, no dc power dissipation, and depletion FET implementation without level shifting diodes.

  18. First Results of the Testing of the Liquid Gallium Jet Limiter Concept for ISTTOK

    SciTech Connect

    Gomes, R. B.; Fernandes, H.; Silva, C.; Borba, D.; Carvalho, B.; Varandas, C. [Associacao EURATOM/IST, Centro de FuSao Nuclear, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Lielausis, O.; Klyukin, A.; Platacis, E.; Mikelsons, A.; Platnieks, I. [Association EURATOM/University of Latvia, Institute of Physics, 32 Miera Str., Salaspils, LV-2169 (Latvia)

    2006-12-04

    The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently the most promising materials are Lithium and Gallium. ISTTOK, a small size tokamak, will be used to test the behavior of a liquid Gallium jet in the vacuum chamber and its influence on the plasma. This paper presents a description of the conceived setup as well as experimental results. The liquid Gallium jet is generated by hydrostatic pressure and injected in a radial position close to a moveable stainless steel limiter. Both the jet and the limiter positions are variable allowing for a controlled exposure of the liquid Gallium to the edge plasma. The main components of the Gallium loop are a MHD pump, the liquid metal injector and a filtering system. The MHD pump is of the induction type, based on rotating permanent magnets. The injector is build from a stainless steel pipe ended by a shaping nozzle. A setup has been developed to introduce oxide-free Gallium inside the loop's main supply tank. Raw liquid metal is placed inside a chamber heated and degassed under high vacuum while clean Gallium is extracted from the main body of the liquefied metal. Prior to installation on the tokamak, the experimental rig has been implemented using a Pyrex tube as test chamber to investigate the stability of the Gallium jet and its break-up length for several nozzle sizes. Results are presented in this paper. This rig was also useful to assess the behavior of the overall implemented apparatus.

  19. Gallium Nitrate for Acute Treatment of Cancer-related Hypercalcemia: Clinicopharmacological and Dose Response Analysis1

    Microsoft Academic Search

    Raymond P. Warrell; Anastasia Skelos; Nancy W. Alcock; Richard S. Bockman

    Current treatment of cancer-related hypercalcemia is limited by agents of limited effectiveness or excessive toxicity. Gallium nitrate is a new drug which both inhibits bone résorption and increases calcium content of bone. We have now treated 39 episodes of hypercalcemia with gallium nitrate administered as a continuous i.v. infusion for 5-7 days at 3 daily dose levels (100 and 200

  20. The determination of titanium, germanium and gallium by charged particle activation analysis

    E-print Network

    Novak, Leo Robert

    1975-01-01

    of MASTER OF SCIENCE May 1975 Major Subject: Chemistry THE DETERMINATION OF TITANIUM GERMANIUM AND GALLIUM BY CHARGED PARTICLE ACTIVATION ANALYSIS A Thesis by LEO ROBERT NOVAK Approved as to style and content by: (Chairman of Committee) Emile A.... Schweikert (Head of Department) Arthur E. Martell (Member) Marvin W. Rowe (Member) Lloyd E. Fite May 1975 AB STRACT The Determination of Titanium, Germanium and Gallium by Charged Particle Activation Analysis (May 1975) Leo Robert Novak, B. S...

  1. Synthesis and single crystal growth of gallium phosphide by the liquid encapsulated vertical Bridgman technique

    Microsoft Academic Search

    K Govinda Rajan; N V Chandra Shekar; G V N Rao; A J Singh; R M Iyer

    1988-01-01

    Gallium phosphide is a typical III–V compound semiconductor and is also an important electronic material. The synthesis and\\u000a single crystal growth of this compound by melt methods is rendered very difficult because of the large phosphorus vapour pressure.\\u000a A high pressure vessel with internal heating and a quartz reactor was first developed for the direct synthesis of gallium\\u000a phosphide. The

  2. Transparent ring oscillator based on indium gallium oxide thin-film transistors

    Microsoft Academic Search

    R. E. Presley; D. Hong; H. Q. Chiang; C. M. Hung; R. L. Hoffman; J. F. Wager

    2006-01-01

    Highly transparent ring oscillators, exhibiting ?75% optical transmittance in the visible portion of the electromagnetic spectrum, are fabricated using indium gallium oxide as the active channel material and standard photolithography techniques. The n-channel indium gallium oxide transparent thin-film transistors (TTFTs) exhibit a peak incremental mobility of ?7cm2V?1s?1 and turn-on voltage of ?2V. A five-stage ring oscillator circuit (which does not

  3. Haemophilus parainfluenzae bacteremia associated with a pacemaker wire localized by gallium scan

    SciTech Connect

    Rosenbaum, G.S.; Calubiran, O.; Cunha, B.A. (Winthrop-Univ. Hospital, Mineola, NY (USA))

    1990-05-01

    A young woman with a history of sick sinus syndrome and placement of a permanent pacemaker 6 months before admission had fever and Haemophilus parainfluenzae bacteremia. A gallium scan localized the infection to the site of the pacemaker wire. Echocardiograms were negative for any vegetations. The patient responded to cefotaxime and trimethoprim-sulfamethoxazole therapy. We believe that this is the first case of H. parainfluenzae bacteremia associated with a pacemaker wire and localized by gallium scan.

  4. Gallium compounds in solar cells. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    Not Available

    1993-12-01

    The bibliography contains citations concerning the use of gallium compounds in solar cells to increase solar cell efficiency. Computer models, theories, and performance tests are included. Gallium compounds used in thin film cells, cascade solar cells, large area solar cells, cells designed for industrial and space applications, and as antireflection coatings are discussed. Resistance to radiation damage, cooling to improve efficiency, grain boundary behavior, and economic considerations are also covered. (Contains 250 citations and includes a subject term index and title list.)

  5. Fabrication and properties of gallium phosphide variable colour displays

    NASA Technical Reports Server (NTRS)

    Effer, D.; Macdonald, R. A.; Macgregor, G. M.; Webb, W. A.; Kennedy, D. I.

    1973-01-01

    The unique properties of single-junction gallium phosphide devices incorporating both red and green radiative recombination centers were investigated in application to the fabrication of monolithic 5 x 7 displays capable of displaying symbolic and alphanumeric information in a multicolor format. A number of potentially suitable material preparation techniques were evaluated in terms of both material properties and device performance. Optimum results were obtained for double liquid-phase-epitaxial process in which an open-tube dipping technique was used for n-layer growth and a sealed tipping procedure for subsequent p-layer growth. It was demonstrated that to prepare devices exhibiting a satisfactory range of dominant wavelengths which can be perceived as distinct emission colors extending from the red through green region of the visible spectrum involves a compromise between the material properties necessary for efficient red emission and those considered optimum for efficient green emission.

  6. Giant topological nontrivial band gaps in chloridized gallium bismuthide.

    PubMed

    Li, Linyang; Zhang, Xiaoming; Chen, Xin; Zhao, Mingwen

    2015-02-11

    Quantum spin Hall (QSH) effect is promising for achieving dissipationless transport devices but presently is achieved only at extremely low temperature. Searching for the large-gap QSH insulators with strong spin-orbit coupling (SOC) is the key to increase the operating temperature. We demonstrate theoretically that this can be solved in the chloridized gallium bismuthide (GaBiCl2) monolayer, which has nontrivial gaps of 0.95 eV at the ? point, and 0.65 eV for bulk, as well as gapless edge states in the nanoribbon structures. The nontrivial gaps due to the band inversion and SOC are robust against external strain. The realization of the GaBiCl2 monolayer will be beneficial for achieving QSH effect and related applications at high temperatures. PMID:25625786

  7. A high open-circuit voltage gallium nitride betavoltaic microbattery

    NASA Astrophysics Data System (ADS)

    Cheng, Zaijun; Chen, Xuyuan; San, Haisheng; Feng, Zhihong; Liu, Bo

    2012-07-01

    A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p-i-n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63Ni source with activity of 0.5 mCi, the open-circuit voltage of the fabricated microbattery with 2 × 2 mm2 area reaches as much as 1.64 V, which is the record value reported for betavoltaic batteries with 63Ni source, the short-circuit current was measured as 568 pA and the conversion effective of 0.98% was obtained. The experimental results suggest that GaN is a high-potential candidate for developing the betavoltaic microbattery.

  8. Electrical and mechanical properties of vapour grown gallium monotelluride crystals

    NASA Astrophysics Data System (ADS)

    Reshmi, P. M.; Kunjomana, A. G.; Chandrasekharan, K. A.

    2013-10-01

    The physical vapour deposition (PVD) of gallium monotelluride (GaTe) in different crystalline habits was established in the growth ampoule, strongly depending on the temperature gradient. Proper control on the temperatures of source and growth zones in an indigenously fabricated dual zone furnace could yield the crystals in the form of whiskers and spherulites. Optical and electron microscopic images were examined to predict the growth mechanism of morphologies. The structural parameters of the grown spherulites were determined by X-ray powder diffraction (XRD). The stoichiometric composition of these crystals was confirmed using energy dispersive analysis by X-rays (EDAX). The type and nature of electrical conductivity were identified by the conventional hot probe and two probe methods, respectively. The mechanical parameters, such as Vickers microhardness, work hardening index, and yield strength, were deduced from microindentation measurements. The results show that the vapour grown p-GaTe crystals exhibit novel physical properties, which make them suitable for device applications.

  9. Sequential technetium-99m HMDP-gallium-67 citrate imaging for the evaluation of infection in the painful prosthesis

    SciTech Connect

    Merkel, K.D.; Brown, M.L.; Fitzgerald, R.H. Jr.

    1986-09-01

    In order to evaluate the clinical utility of sequential technetium-99m HMDP-gallium-67 scanning in patients with painful orthopedic prosthesis, a retrospective review was made of 154 sequential scans performed in 130 patients. Criteria for a positive study included spatially incongruent gallium-technetium uptake or gallium uptake that was congruent but more intense than technetium. Images were interpreted as negative if gallium was congruent and less intense than technetium. Sixty-six patients underwent surgery (31 infected, 35 aseptic), and 64 were evaluated clinically (3 infected, 61 aseptic). The combined results of the surgical and nonsurgical patients yielded a sensitivity of 66%, a specificity of 81%, and an accuracy of 77%. In this series, the technetium-gallium scan combination has proven to be helpful but more recent techniques such as indium-111-labeled leukocytes may prove to be superior to sequential technetium-gallium imaging.

  10. Study of Magnetohydrodynamic Surface Waves on Liquid Gallium

    SciTech Connect

    Hantao Ji; William Fox; David Pace; H.L. Rappaport

    2004-05-13

    Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed.

  11. Study of liquid gallium at high pressure using synchrotron x-ray

    SciTech Connect

    Yu, Tony; Guo Quanzhong; Parise, John [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); Chen Jiuhua [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); Department of Mechanical and Materials Engineering, Center for the Study of Matters at Extreme Conditions, Florida International University, Miami, Florida 33199 (United States); Ehm, Lars [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States); Huang Shu [Department of Mechanical and Materials Engineering, Center for the Study of Matters at Extreme Conditions, Florida International University, Miami, Florida 33199 (United States); Luo Shengnian [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2012-06-01

    Liquid gallium has been studied at high pressure up to 2 GPa and ambient temperature in a diamond anvil cell using high energy synchrotron x-ray beam. The total x-ray scattering data of liquid gallium were collected up to Q = 12 A{sup -1} and analyzed using pair distribution functions (PDF). The results indicate that the first nearest neighbor peak and second nearest neighbor (shoulder) peak of PDF in liquid gallium does not change with pressure, whereas the higher order (i.e., third and fourth) nearest neighbor peaks shift towards shorter distance with increasing pressure. Reverse Monte Carlo modeling based on the observed data shows that the coordination number in the liquid gallium increases with pressure from 10.5 at 0.3 GPa to 11.6 at 2 GPa. An atomic arrangement similar to the crystalline phase of Ga(II) with coordination number of 12 is proposed for the locally dense-packed rigid unit in liquid gallium. The volume compression data derived from the structure modeling yield a bulk modulus of 12.1(6) GPa for liquid gallium.

  12. Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

    SciTech Connect

    Wissman, J., E-mail: jwissman@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Finkenauer, L. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Deseri, L. [DICAM, Department of Mechanical, Civil and Environmental Engineering, University of Trento, via Mesiano 77 38123 Trento (Italy); TMHRI-Department of Nanomedicine, The Methodist Hospital Research Institute, 6565 Fannin St., MS B-490 Houston, Texas 77030 (United States); Mechanics, Materials and Computing Center, CEE and ME-CIT, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Majidi, C. [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Robotics Institute and Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2014-10-14

    We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K<0). Applying voltage ? to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ?. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of ?. Based on this theory, we predict a dependency of ? on ? that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

  13. LO-plasmon modes in doped gallium arsenide/aluminum gallium arsenide superlattices

    NASA Astrophysics Data System (ADS)

    Rodgers, Robert A.

    2011-12-01

    A great deal of interest has emerged in recent years to design novel compound semiconductor materials to fulfill the growing societal needs of efficient light sources, powerful solar cells, miniaturized-electronic-circuitry for lab-on-chip equipment, and a plethora of handheld opto-electronic devices. GaAs-based III-V compounds are significant materials with important fundamental characteristics allowing the scientists and engineers to envision their use in a variety of devices including light-emitting diodes (LEDs), laser diodes (LDs), and high-electron mobility transistors (HEMTs). In this regard, there has been a growing interest of studying the far-infrared optical properties in both un-doped and doped bulk III-V compounds, thin films, ternary alloys, and their nano-structured quantum-wells and superlattices. For GaAs/AlxGa1-xAs materials grown especially by molecular-beam epitaxy (MBE), the optical constants [viz., n, k, N (Charge carrier concentration), R (Reflection), and T (Transmission)] over a broad frequency regime are fundamental inputs that must be known for constructing opto-electronic devices. Despite some success by using Raman Spectroscopy, the influence of free charge carrier concentration on the phonon-plasmon coupled modes (L+/-) by far-infrared (FIR) spectroscopy are still scantily known. Any effort to extract accurate information about the charge carrier concentration N in either n- or p-type doped III-V compounds using FIR would be of significant importance to the scientific community. In this thesis, we will use the electromagnetic theory to study the IR reflectivity and transmission at oblique incidence in both undoped and doped GaAs, AlxGa1-xAs thin films and superlattices in order to correlate the shifts of the L+/- mode frequencies with the free charge carrier concentration. The transmission study in compound semiconductors for s-polarization reveals a single minimum at the resonance frequency of the TO mode, while for p-polarization the transmission minima occur at both the resonance frequencies of the TO and LO modes. In doped semiconductor thin films, the transmission in p-polarization exhibits minima at TO and L+ with a shift of L+ mode to higher frequency as the charge carrier concentration increases.

  14. Growth and analysis of gallium arsenide-gallium antimonide single and two-phase nanoparticles

    NASA Astrophysics Data System (ADS)

    Schamp, Crispin T.

    When evaluating the path of phase transformations in systems with nanoscopic dimensions one often relies on bulk phase diagrams for guidance because of the lack of phase diagrams that show the effect of particle size. The GaAs-GaSb pseudo-binary alloy is chosen for study to gain insight into the size dependence of solid-solubility in a two-phase system. To this end, a study is performed using independent laser ablation of high purity targets of GaAs and GaSb. The resultant samples are analyzed by transmission electron microscopy. Experimental results indicate that GaAs-GaSb nanoparticles have been formed with compositions that lie within the miscibility gap of bulk GaAs-GaSb. An unusual nanoparticle morpohology resembling the appearance of ice cream cones has been observed in single component experiments. These particles are composed of a spherical cap of Ga in contact with a crystalline cone of either GaAs or GaSb. The cones take the projected 2-D shape of a triangle or a faceted gem. The liquid Ga is found to consistently be of spherical shape and wets to the widest corners of the cone, suggesting an energy minimum exists at that wetting condition. To explore this observation a liquid sphere is modeled as being penetrated by a solid gem. The surface energies of the solid and liquid, and interfacial energy are summed as a function of penetration depth, with the sum showing a cusped minimum at the penetration depth corresponding to the waist of the gem. The angle of contact of the liquid wetting the cone is also calculated, and Young's contact angle is found to occur when the derivative of the total energy with respect to penetration depth is zero, which can be a maximum or a minimum depending on the geometrical details. The spill-over of the meniscus across the gem corners is found to be energetically favorable when the contact angle achieves the value of the equilibrium angle; otherwise the meniscus is pinned at the corners.

  15. Influence of novel gallium complexes on the homeostasis of some biochemical and hematological parameters in rats.

    PubMed

    Gârban, Gabriela; Silaghi-Dumitrescu, Radu; Ioni??, Hortensia; Gârban, Zeno; H?d?rug?, Nicoleta-Gabriela; Ghibu, George-Daniel; Balt?, Cornel; Simiz, Florin-Dan; Mitar, Carmen

    2013-12-01

    The aim of this study was to detect possible homeostasis changes in some biochemical and hematological parameters after the administration of gallium (Ga) complexes C (24) and C (85) on an experimental animal model (Wistar strain rats). In order to observe chronobiological aspects, a morning (m) and an evening (e) animal series were constituted. Further on, each series were divided into three groups: control (C), experimental I (EI), and experimental II (EII). Both Ga complexes were solubilized in a carrier solution containing polyethylene glycol (PEG) 400, water, and ethanol. Animals of the C groups received the carrier solution by intraperitoneal injection, those from the EI groups received the solubilized C(24) gallium complex, and those of the EII groups received the solubilized C(85) gallium complex. At the end of the experiment, blood and tissue samples were taken and the following parameters were determined: serum concentration of the nonprotein nitrogenous compounds (uric acid, creatinine, and blood urea nitrogen), hematological parameters (erythrocytes, hemoglobin, leukocytes, and platelets), and the kidney tissue concentration of three essential trace elements (Fe, Cu, and Zn). With the exception of uric acid, the results revealed increased concentrations of the nonprotein nitrogenous compounds both in the morning and in the evening experimental groups. Hematological data showed increased levels of erythrocytes, hemoglobin, and leukocytes and decreased platelet levels in the experimental group given the C(24) gallium complex in the morning (EI-m) group; increased levels of leukocytes and decreased levels of the other parameters in the experimental group given the C(24) gallium complex in the evening (EI-e) group; and increased levels of all hematological parameters in the experimental groups receiving the C(85) gallium complex in the morning (EII-m) group and in the evening (EII-e) group. Decreased kidney tissue concentrations of metals were found in all the experimental groups. Fe levels were significantly decreased in the EI-m receiving the C(24) gallium complex and EII-m which received the C(85) gallium complex and in the EII-e group which received the C(85) gallium complex. In the EI-e group which received the C(24) gallium complex, a significant decrease of Cu concentration was reported. PMID:23990509

  16. Pulmonary gallium uptake in rats with granulomatosis induced by complete Freund adjuvant

    SciTech Connect

    Stanislas-Leguern, G.; Masse, R.; Jaubert, F.; Chretien, J.; Huchon, G.

    1988-01-01

    To investigate the mechanism of gallium-67 uptake in lung granulomatosis, we studied 13 rats in which lung granulomatosis was induced by injection of complete Freund adjuvant (CFA) and 14 controls. Gallium uptake was assessed in bronchoalveolar lavage fluid and lavaged lung. The cells responsible for gallium uptake were identified by latent image activation autoradiography. Gallium activity in both lavaged lungs and bronchoalveolar cells (BAC) was higher in CFA-treated animals than in controls (172,205 +/- 134,783 DPM versus 44,456 +/- 14,486 DPM +/- SD (p less than 0.05) and 40,083 +/- 16,350 DPM versus 9100 +/- 4114 DPM (p less than 0.05), respectively). In control rats, about two-thirds of total lung gallium was located in the interstitium, whereas in CFA-treated rats it was found in the mononuclear cells of lung granulomas. Gallium tracks were more numerous in the alveolar macrophages (AM) of CFA-treated rats than in control AM (28.4 +/- 10.0/field versus 8.4 +/- 3.8/field, p less than 0.001) but the number of tracks was proportional to the number of AM (52.4 +/- 18.7 versus 12.2 +/- 4.3, respectively; p less than 0.001). It is concluded that in rats with CFA-induced lung granulomatosis 1) pulmonary gallium uptake increases, 2) mononuclear cells are responsible for this uptake in both granulomas and AM, and 3) the increased uptake is due to the increased number of mononuclear cells.

  17. Antitumor efficacy and tolerability of systemically administered gallium acetylacetonate-loaded gelucire-stabilized nanoparticles.

    PubMed

    Wehrung, Daniel; Bi, Lipeng; Geldenhuys, Werner J; Oyewumi, Moses O

    2013-06-01

    The widespread clinical success with most gallium compounds in cancer therapy is markedly hampered by lack of tumor specific accumulation, poor tumor permeability and undesirable toxicity to healthy tissues. The aim of this work was to investigate for the first time antitumor mechanism of a new gallium compound (gallium acetylacetonate; GaAcAc) while assessing effectiveness of gelucire-stabilized nanoparticles (NPs) for potential application in gallium-based lung cancer therapy. NPs loaded with GaAcAc (Ga-NPs) were prepared using mixtures of cetyl alcohol with Gelucire 44/14 (Ga-NP-1) or Gelucire 53/13 (Ga-NP-2) as matrix materials. Of special note from this work is the direct evidence of involvement of microtubule disruption in antitumor effects of GaAcAc on human lung adenocarcinoma (A549). In-vivo tolerability studies were based on plasma ALT, creatinine levels and histopathological examination of tissues. The superior in-vivo antitumor efficacy of Ga-NPs over GaAcAc was depicted in marked reduction of tumor weight and tumor volume as well as histological assessment of excised tumors. Compared to free GaAcAc, Ga-NPs showed a 3-fold increase in tumor-to-blood gallium concentrations with minimized overall exposure to healthy tissues. Overall, enhancement of antitumor effects of GaAcAc by gelucire-stabilized NPs coupled with reduced exposure of healthy tissues to gallium would likely ensure desired therapeutic outcomes and safety of gallium-based cancer treatment. PMID:23858967

  18. Turbine Blade Alloy

    NASA Technical Reports Server (NTRS)

    MacKay, Rebecca

    2001-01-01

    The High Speed Research Airfoil Alloy Program developed a fourth-generation alloy with up to an +85 F increase in creep rupture capability over current production airfoil alloys. Since improved strength is typically obtained when the limits of microstructural stability are exceeded slightly, it is not surprising that this alloy has a tendency to exhibit microstructural instabilities after high temperature exposures. This presentation will discuss recent results obtained on coated fourth-generation alloys for subsonic turbine blade applications under the NASA Ultra-Efficient Engine Technology (UEET) Program. Progress made in reducing microstructural instabilities in these alloys will be presented. In addition, plans will be presented for advanced alloy development and for computational modeling, which will aid future alloy development efforts.

  19. (Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1999. Two companies in

    E-print Network

    wafers. Commercial shipments of blue and blue-violet gallium nitride (GaN)-based laser diodes and blue in optoelectronic devices, which include light-emitting diodes (LED's), laser diodes, photodetectors, and solar LED's began early in the year from a Japanese firm. Large-scale applications for the blue laser diodes

  20. Surface acoustic waves and acousto-optical effects in aluminum gallium nitrides

    NASA Astrophysics Data System (ADS)

    Bu, Gang

    Aluminum nitride, gallium nitride, and their alloys possess piezoelectric properties, which make them potential materials for surface acoustic wave (SAW) applications. The propagation of the Rayleigh-type and leaky surface acoustic waves (LSAW) has been studied in bulk and layered nitrides theoretically and experimentally. Low temperature coefficient of frequency (TCF) of -16 ppm/°C (for Rayleigh wave), high velocity (˜11000 m/s for second leaky) and reasonably large K2 (˜0.5%) have been obtained for the a-plane c -propagation AlN single-crystal substrates. A full set of elastic and piezoelectric constants of AlN has also been extracted by measuring the SAW and LSAW velocities and K2 values in c-plane and a-plane samples in various directions. With an AIN layer deposited on Z-cut LiNbO3, the phase velocity increased slightly (˜1%), TCF was improved by 15%, but the K2 value decreased by about 50% at kh = 0.1, compared to LiNbO3 substrate. Using the prism coupling method at optical wavelength 633 nm, we measured the effective refractive indices of guided optical modes in AlxGa 1-xN-on-sapphire structure. From these measurements, the ordinary and extraordinary refractive indices and thicknesses of the layers were evaluated. By fitting our experimental values to the data published in literature, we determined the energy bandgaps and molar fractions of Al in our samples. Also a straightforward method was realized to characterize the attenuation of guided modes by employing a CCD system. One of the promising applications of the SAW in nitrides is the acousto-optical (AO) control of guided optical waves, which provides a potential of the integration of the light source, controlling electronics and the SAW device on the same chip. The acousto-optic diffraction of guided optical waves from the SAWS in AlxGa1-xN-on-sapphire structure was studied. In the near-to-Bragg diffraction regime, the diffraction efficiency from 90 to 95% was attained at SAW powers of 0.28 W and 0.72 W for the blue and red light respectively. The increase in the diffraction efficiency with the decreasing optical wavelength is in a good agreement with the theoretical prediction. This feature makes AlGaN very promising for AO applications in the deep UV region.

  1. Ductile alloy and process for preparing composite superconducting wire

    DOEpatents

    Verhoeven, John D. (Ames, IA); Finnemore, Douglas K. (Ames, IA); Gibson, Edwin D. (Ames, IA); Ostenson, Jerome E. (Ames, IA)

    1983-03-29

    An alloy for the commercial production of ductile superconducting wire is prepared by melting together copper and at least 15 weight percent niobium under non-oxygen-contaminating conditions, and rapidly cooling the melt to form a ductile composite consisting of discrete, randomly distributed and orientated dendritic-shaped particles of niobium in a copper matrix. As the wire is worked, the dendritric particles are realigned parallel to the longitudinal axis and when drawn form a plurality of very fine ductile superconductors in a ductile copper matrix. The drawn wire may be tin coated and wound into magnets or the like before diffusing the tin into the wire to react with the niobium. Impurities such as aluminum or gallium may be added to improve upper critical field characteristics.

  2. Optimization stability of gate dielectrics on gallium nitride

    NASA Astrophysics Data System (ADS)

    Hlad, Mark Steven

    The application of gallium nitride (GaN)-based devices requires the use of a gate dielectric to reduce gate leakage, passivate surface traps, and provide isolation between devices. It is critical for the insulator to remain chemically and thermally stable at high temperatures (i.e., 1000°C) during device fabrication and operation. More importantly, it must possess good electrical characteristics such as a high breakdown field, low flatband voltage shift, and low interface trapped charge (Dit). A new dielectric material, known as scandium gallium oxide ((Sc2O3)x(Ga 2O3)1-x), was investigated. Growth conditions of MgxScyOz and MgO were also optimized to enhance their environmental stability and improve their electrical results. All dielectric films were deposited by molecular beam epitaxy (MBE), which uses independent sources to precisely control the film thickness and stoichiometry. Initial films on GaN were characterized by using a wide variety of techniques to determine the crystal structure, surface roughness, chemical composition, and film thickness. Electrical diodes were then fabricated for electrical testing such as current-voltage and capacitance-voltage measurements. Continuous and digital growth techniques for (Sc2O3) x(Ga2O3)1-x revealed segregation of Ga at the surface. The segregation was eliminated by utilizing a growth technique in which the Ga shutter was closed for a set amount of time towards the end of the growth while the O and Sc shutters remained open. A poor breakdown field of 0.15 MV/cm was obtained due to the presence of free Ga metal in the film. Growth of MgxScyOz at low oxygen pressures showed breakdown fields as high as 4 MV/cm and Dit values in the low 1011 ev-1cm-2 range, but flatband voltage shift values ranging from 3.83-5.30 V were also obtained. The large flatband voltage shifts were attributed to defects generated from the mixed Sc (+3) and Mg (+2) valences. Optimization of MgO growth parameters at low oxygen pressures and low growth rates showed improved environmental stability and good electrical results on both u-GaN and p-GaN. The use of a new processing scheme in which the ohmic metal is deposited prior to MgO showed good feasibility as it displayed comparable electrical results to the old scheme involving MgO deposition prior to ohmic metallization.

  3. Micro and nano-structured green gallium indium nitride/gallium nitride light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Stark, Christoph J. M.

    Light-emitting diodes (LEDs) are commonly designed and studied based on bulk material properties. In this thesis different approaches based on patterns in the nano and micrometer length scale range are used to tackle low efficiency in the green spectral region, which is known as “green gap”. Since light generation and extraction are governed by microscopic processes, it is instructive to study LEDs with lateral mesa sizes scaled to the nanometer range. Besides the well-known case of the quantum size effect along the growth direction, a continuous lateral scaling could reveal the mechanisms behind the purported absence of a green gap in nanowire LEDs and the role of their extraction enhancement. Furthermore the possibility to modulate strain and piezoelectric polarization by post growth patterning is of practical interest, because the internal electric fields in conventional wurtzite GaN LEDs cause performance problems. A possible alternative is cubic phase GaN, which is free of built-in polarization fields. LEDs on cubic GaN could show the link between strong polarization fields and efficiency roll-off at high current densities, also known as droop. An additional problem for all nitride-based LEDs is efficient light extraction. For a planar GaN LED only roughly 8% of the generated light can be extracted. Novel lightextraction structures with extraction-favoring geometry can yield significant increase in light output power. To investigate the effect of scaling the mesa dimension, micro and nano-sized LED arrays of variable structure size were fabricated. The nano-LEDs were patterned by electron beam lithography and dry etching. They contained up to 100 parallel nano-stripe LEDs connected to one common contact area. The mesa width was varied over 1 ?m, 200 nm, and 50 nm. These LEDs were characterized electrically and optically, and the peak emission wavelength was found to depend on the lateral structure size. An electroluminescence (EL) wavelength shift of 3 nm towards smaller values was observed when the stripe width was reduced from 1 ?m to 50 nm. At the same time a strong fourfold enhancement of the light emission from the patterned region over the unpatterned area was observed. Micro-patterned LEDs showed non-linear scaling of the light output power, and an enhancement of 39 % was achieved for structures with an area fill ratio of 0.5 over an LED with square mesa. Growth of cubic GaN and cubic GaInN/GaN LEDs was shown by M-OVPE in Vshaped grooves formed by the {111} planes of etched silicon. SEM images of the GaN layer in small ( 0.5 ?m) regions show a contrast change where the phase boundary between cubic and wurtzite GaN is expected to occur. The growth parameter space is explored for optimal conditions while minimizing the alloying problem for GaN growth on Si. The cubic GaN phase is confirmed by electron back-scatter diffraction (EBSD) in the V-groove center, whereas wurtzite GaN is found near the groove edges. Luminescence of undoped GaN and GaInN/GaN multi-quantum well structures was studied by cathodoluminescence (CL). The undoped cubic GaN structure showed strong band-edge luminescence at 385 nm (3.22 eV) at 78 K, whereas for the MQW device strong emission at 498 nm is observed, even at room temperature. Full cubic LED structures were grown, and wavelength-stable electroluminescence at 489 nm was demonstrated. LEDs with integrated light extraction structures are grown on free-standing GaN substrates with different off-cut angles. The devices with different off-cut show pronounced features at the top surface that also penetrate the active region. For a 2.24° off-cut, these features resemble fish scales, where the feature sizes are in the ?m-range. The 2.24° off-cut LED shows a 3.6-fold increased light output power compared to a LED on virtually on-axis substrate with 0.06° off-cut. The enhancement found in the fish scale LEDs is attributed to increased light scattering, effectively reducing the fraction of trapped light. These results show the potential of structures on the micro and nanometer scale

  4. Phase Coexistence in Gallium Nanoparticles Controlled by Electron Excitation S. Pochon, K. F. MacDonald, R. J. Knize,* and N. I. Zheludev

    E-print Network

    Zheludev, Nikolay

    . The single elec- tron ionization cross section is about 1 0:7 10ÿ16 cm2 while the total higher orderPhase Coexistence in Gallium Nanoparticles Controlled by Electron Excitation S. Pochon, K. F. Mac in gallium nanoparticles under electron-beam excitation. Our study of electron-beam excitation of gallium

  5. Elimination of arthritis pain and inflammation for over 2 years with a single 90 min, topical 14% gallium nitrate treatment: case reports and review of actions of gallium III.

    PubMed

    Eby, George

    2005-01-01

    Arthritis is inflammation in a joint often with joint damage, usually accompanied by pain, swelling and stiffness, resulting from infection, trauma, degenerative changes, metabolic disturbances, autoimmune or other causes. It occurs in various forms, including rheumatoid arthritis, osteoarthritis, bacterial arthritis and gout. Gallium III can inhibit the production of inflammatory cytokines, such as IL-1beta, produced by macrophage-like cells in vitro. A dose-dependent inhibition of IL-1beta and TPA stimulated MMP activity by gallium nitrate at increasing concentrations occurs, demonstrating that gallium nitrate can be a useful modulator of inflammation in arthritis. Gallium III is an inhibitor of bone resorption and is an effective treatment for hypercalcemia. Gallium III has been reported to be effective in the treatment of mycobacterium butycicum-induced arthritis in rats by antagonism of iron III. Long-term elimination of pain from arthritis by gallium III was first observed in horses primarily being treated for navicular disease. Several people treating their horses with gallium nitrate coincidentally found that arthritis pain in their fingers ended and did not return after soaking their hands in 14% gallium nitrate solution. Therefore, the severely arthritic hands of a 60-year-old woman were topically treated with a 14% aqueous solution of gallium nitrate for 90 min. Pain and inflammation from rheumatoid arthritis diminished rapidly, and neither pain nor inflammation returned during the following 2 years from that single treatment. A 61-year-old woman who had osteoarthritis in her left knee, shoulders and wrists was treated orally with 50 ml of a 1% gallium nitrate solution (120 mg elemental gallium) daily using a two week on and two week off protocol, resulting in almost total elimination of pain while on gallium nitrate, while pain partially returned during the two week off periods. Treatment of frozen shoulder with topical 40% gallium nitrate for 120 min resulted in greatly reduced pain and crepitus almost immediately with complete restoration of range of motion, with pain remaining essentially absent for over 1 year. Mechanisms of action are hypothesized to include anti-inflammatory, bone density improvements, antibacterial, anti-iron III and anti-aluminum III effects. Proper use of gallium III may be effective in terminating pain and inflammation of arthritis for years, often with a single treatment. PMID:16122880

  6. Planning mantle radiation therapy in patients with Hodgkin disease: role of gallium-67 scintigraphy

    SciTech Connect

    Jochelson, M.S.; Herman, T.S.; Stomper, P.C.; Mauch, P.M.; Kaplan, W.D.

    1988-12-01

    Detection of all sites of lymphoma is imperative for accurate planning of radiation therapy. In patients with Hodgkin disease, mantle radiation is used to treat the thoracic lymph nodes; in those with early-stage or nonbulky disease, mantle and paraaortic radiation may be the only treatment given. CT scanning of the chest adds important information to that obtained from chest radiographs. Gallium-67 scintigraphy has also been used to provide additional information on sites of active tumor. To determine the usefulness of 67Ga-citrate scintigraphy in planning the portals for radiation therapy, we analyzed the radiation treatment plans in 26 consecutive patients with Hodgkin disease; in all 26 patients, the disease had been staged by chest radiographs, chest CT scans, and gallium-67 images. Gallium-67 imaging alone provided unique information that affected the treatment plans in three patients (12%). The combined results of gallium-67 imaging and CT scans influenced the planning of radiation therapy in eight patients (31%). Gallium-67 imaging was found to be an important adjunctive study for optimal planning of radiation therapy in patients with Hodgkin disease.

  7. Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens

    SciTech Connect

    Novetsky, G.J.; Turner, D.A.; Ali, A.; Raynor, W.J.; Fordham, E.W.

    1981-11-01

    Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) no preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after adminstration of castor oil than after no prepartion (p = 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p = 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

  8. Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens

    SciTech Connect

    Novetsky, G.J.; Turner, D.A.; Ali, A.; Raynor, W.J. Jr.; Fordham, E.W.

    1981-01-01

    Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) not preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after administration of castor oil than after no preparation (p . 0.047). A high fiber diet also resulted in a substantial reduction of colonic activity when compared with no preparation; the difference, however, was not statistically significant (p . 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p . 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

  9. (Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

    DOEpatents

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

    2002-01-01

    The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

  10. (Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

    DOEpatents

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

    2001-01-01

    The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

  11. Direct Synthesis of Gallium Nitride Nanowires Coated with Boron Carbonitride Layers Hee Won Seo, Seung Yong Bae, and Jeunghee Park*

    E-print Network

    Kim, Bongsoo

    Direct Synthesis of Gallium Nitride Nanowires Coated with Boron Carbonitride Layers Hee Won Seo-crystalline wurtzite-structured gallium nitride nanowires. The graphitic outerlayers are composed of boron, carbonN nanorods.19 They also synthesized GaN nanorods coated with boron nitride (BN) layers.20 The mixture of Ga

  12. Extrusion of aluminium alloys

    SciTech Connect

    Sheppard, T.

    1999-01-01

    In recent years the importance of extruded alloys has increased due to the decline in copper extrusion, increased use in structural applications, environmental impact and reduced energy consumption. There have also been huge technical advances. This text provides comprehensive coverage of the metallurgical, mathematical and practical features of the process. The contents include: continuum principles; metallurgical features affecting the extrusion of Al-alloys; extrusion processing; homogenization and extrusion conditions for specific alloys; processing of 6XXX alloys; plant utilization; Appendix A: specification of AA alloys and DIN equivalents; Appendix B: chemical compositions; and Appendix C: typical properties.

  13. High strength alloys

    DOEpatents

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  14. High strength alloys

    DOEpatents

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  15. Ultra-thin film nanostructured gallium arsenide solar cells

    NASA Astrophysics Data System (ADS)

    Kang, Yangsen; Chen, Yusi; Huo, Yijie; Zhao, Li; Jia, Jieyang; Deng, Huiyang; Harris, James S.

    2014-11-01

    State-of-the-art III-V cells have reached the highest energy conversion efficiency among all types of solar cells. However, these cells are not applicable to widespread terrestrial solar energy system yet due to the high cost of epitaxial growth. Ultra-thin film absorbers with advanced light management is one of the most promising solutions to drive down the cost. In this paper, we present an ultra-thin film nano-window gallium arsenide (GaAs) solar cell design. This ultrathin cell consists of a nano-structured Al0.8Ga0.2As window layer on the front side to reduce the reflection and to trap the light, and a metal reflector on the back side to further increase the light path. The 300 nm thick GaAs cell with Al0.8Ga0.2As nano-window shows a broad band absorption enhancement from visible to near infrared (NIR), achieving a spectrally averaged absorption of 94% under normal incidence. In addition, this cell shows excellent angular absorption properties, achieving over 85% spectral averaged absorption at up to 60 degree off normal incidence. Meanwhile, this structure with planar junction and nano-window has solved the issue of low fill factor and low open-circuit voltage in nano-structured GaAs solar cell. A nano-window cell with a 3 ?m thick GaAs junction demonstrated an open circuit voltage of 0.9V.

  16. Enhanced photothermal conversion in vertically oriented gallium arsenide nanowire arrays.

    PubMed

    Walia, Jaspreet; Dhindsa, Navneet; Flannery, Jeremy; Khodabad, Iman; Forrest, James; LaPierre, Ray; Saini, Simarjeet S

    2014-10-01

    The photothermal properties of vertically etched gallium arsenide nanowire arrays are examined using Raman spectroscopy. The nanowires are arranged in square lattices with a constant pitch of 400 nm and diameters ranging from 50 to 155 nm. The arrays were illuminated using a 532 nm laser with an incident energy density of 10 W/mm(2). Nanowire temperatures were highly dependent on the nanowire diameter and were determined by measuring the spectral red-shift for both TO and LO phonons. The highest temperatures were observed for 95 nm diameter nanowires, whose top facets and sidewalls heated up to 600 and 440 K, respectively, and decreased significantly for the smaller or larger diameters studied. The diameter-dependent heating is explained by resonant coupling of the incident laser light into optical modes of the nanowires, resulting in increased absorption. Photothermal activity in a given nanowire diameter can be optimized by proper wavelength selection, as confirmed using computer simulations. This demonstrates that the photothermal properties of GaAs nanowires can be enhanced and tuned by using a photonic lattice structure and that smaller nanowire diameters are not necessarily better to achieve efficient photothermal conversion. The diameter and wavelength dependence of the optical coupling could allow for localized temperature gradients by creating arrays which consist of different diameters. PMID:25233265

  17. Low-temperature thermal conductivity of terbium-gallium garnet

    SciTech Connect

    Inyushkin, A. V., E-mail: inyushkin@imp.kiae.ru; Taldenkov, A. N. [Kurchatov Institute, Russian Research Centre (Russian Federation)

    2010-11-15

    Thermal conductivity of paramagnetic Tb{sub 3}Ga{sub 5}O{sub 12} (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence {kappa}(T) of thermal conductivity at T{sub min} = 0.52 K. This and other singularities on the {kappa}(T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb{sup 3+} ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb{sup 3+} ion.

  18. Investigation of a Gallium MPD Thruster with an Ablating Cathode

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Polzin, Kurt A.

    2010-01-01

    Arc impedance, exhaust velocity, and plasma probe measurements are presented. The thruster is driven by a 50 microsecond pulse from a 6.2 milliohm pulse forming network, and gallium is supplied to the discharge by evaporation of the cathode. The arc voltage is found to vary linearly with the discharge current with an arc impedance of 6.5 milliohms. Electrostatic probes yield an exhaust velocity that is invariant with the discharge current and has a peak value of 20 kilometers per second, which is in reasonable agreement with the value (16 plus or minus 1 kilometer per second) calculated from the mass bit and discharge current data. Triple probe measurements yield on axis electron temperatures in the range of 0.8-3.8 eV, electron densities in the range of 1.6 x 10(exp 21) to 2.1 x 10(exp 22) per cubic meter, and a divergence half angle of 16 degrees. Measurements within the interelectrode region yield a peak magnetic field of 0.8 T, and the observed radial trends are consistent with an azimuthally symmetric current distribution. A cathode power balance model is coupled with an ablative heat conduction model predicting mass bit values that are within 20% of the experimental values.

  19. Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

    PubMed Central

    Munirathinam, Rajesh; Ricciardi, Roberto; Egberink, Richard J M; Huskens, Jurriaan; Holtkamp, Michael; Wormeester, Herbert; Karst, Uwe

    2013-01-01

    Summary Polystyrene sulfonate polymer brushes, grown on the interior of the microchannels in a microreactor, have been used for the anchoring of gallium as a Lewis acid catalyst. Initially, gallium-containing polymer brushes were grown on a flat silicon oxide surface and were characterized by FTIR, ellipsometry, and X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of one gallium per 2–3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-functionalized brushes in a microreactor was demonstrated for the dehydration of oximes, using cinnamaldehyde oxime as a model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3. PMID:24062830

  20. Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles

    PubMed Central

    Wu, Pae C; Khoury, Christopher G.; Kim, Tong-Ho; Yang, Yang; Losurdo, Maria; Bianco, Giuseppe V.; Vo-Dinh, Tuan; Brown, April S.; Everitt, Henry O.

    2009-01-01

    Size-controlled gallium nanoparticles deposited on sapphire are explored as alternative substrates to enhance Raman spectral signatures. Gallium’s resilience following oxidation is inherently advantageous compared to silver for practical ex vacuo, non-solution applications. Ga nanoparticles are grown using a simple, molecular beam epitaxy-based fabrication protocol, and by monitoring their corresponding surface plasmon resonance energy through in situ spectroscopic ellipsometry, the nanoparticles are easily controlled for size. Raman spectroscopy performed on cresyl fast violet (CFV) deposited on substrates of differing mean nanoparticle size represents the first demonstration of enhanced Raman signals from reproducibly tunable self-assembled Ga nanoparticles. Non-optimized aggregate enhancement factors of ~80 were observed from the substrate with the smallest Ga nanoparticles for CFV dye solutions down to a dilution of 10 ppm. PMID:19655747

  1. Deposition of metallic gallium on re-crystallized ceramic material during focused ion beam milling

    SciTech Connect

    Muñoz-Tabares, J.A., E-mail: j.a.munoz.tabares@gmail.com [Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Cd Universitaria, 04510 México DF, México (Mexico); Anglada, M. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, Universitat Politècnica de Catalunya, Avda. Diagonal 647 (ETSEIB), 08028 Barcelona (Spain); Reyes-Gasga, J. [Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Cd Universitaria, 04510 México DF, México (Mexico)

    2013-12-15

    We report a new kind of artifact observed in the preparation of a TEM sample of zirconia by FIB, which consists in the deposition of metallic gallium nano-dots on the TEM sample surface. High resolution TEM images showed a microstructure of fine equiaxed grains of ? 5 nm, with some of them possessing two particular characteristics: high contrast and well-defined fast Fourier transform. These grains could not be identified as any phase of zirconia but it was possible to identify them as gallium crystals in the zone axis [110]. Based on HRTEM simulations, the possible orientations between zirconia substrate and deposited gallium are discussed in terms of lattice mismatch and oxygen affinity. - Highlights: • We show a new type of artifact induced during preparation of TEM samples by FIB. • Deposition of Ga occurs due to its high affinity for oxygen. • Materials with small grain size (? 5 nm) could promote Ga deposition. • Small grain size permits the elastic accommodation of deposited Ga.

  2. Gallium-based thermal interface material with high compliance and wettability

    NASA Astrophysics Data System (ADS)

    Gao, Yunxia; Liu, Jing

    2012-06-01

    This study reports a gallium-based thermal interface material (GBTIM) consisting of gallium oxides dispersed uniformly into the 99 % gallium metal. The wettability of GBTIM with other materials is disclosed and compared. The thermal conductivity of GBTIM measured by a computer-controlled Mathis TCi thermal analyzer is ˜13.07 W m-1 K-1 at room temperature, which is significantly higher than that of conventional thermal greases. An experimental facility is described to measure the thermal resistance across the GBTIM under steady-state conditions and the thermal interface resistance is measured as low as 2.6 mm2 kW-1 with a pressure of 0.05 MPa, which is an order lower than that of the best commercialized thermal greases. Further, the GBTIM is formed into a desired shape to enhance thermal transfer, such as semi-liquid paste or thermal pad, which can be cut into a required shape.

  3. Gallium scanning in differentiating malignant from benign asbestos-related pleural disease

    SciTech Connect

    Teirstein, A.S.; Chahinian, P.; Goldsmith, S.J.; Sorek, M.

    1986-01-01

    In order to assess the utility of 67gallium citrate in delineating malignant pleural mesothelioma from benign asbestos-related pleural disease, 49 patients with malignant mesothelioma and 16 with benign asbestos-related pleural disease were studied. Seven patients with malignant mesothelioma had no history of asbestos exposure, while the remaining 58 patients were exposed. Forty-three of the 49 patients (88%) with malignant mesothelioma had a positive 67gallium scan including 36 of the 42 (86%) patients with asbestos exposure and all 7 patients without a history of asbestos exposure. Three of 16 patients (19%) with benign asbestos-related pleural disease had a positive scan. 67Gallium radionuclide imaging is nonspecific but may be valuable in noninvasive monitoring of asbestos-exposed populations, which have a high risk for the late development of benign and/or malignant pleural disease.

  4. Total neutron scattering investigation of the structure of a cobalt gallium oxide spinel prepared by solvothermal oxidation of gallium metal

    NASA Astrophysics Data System (ADS)

    Playford, Helen Y.; Hannon, Alex C.; Tucker, Matthew G.; Lees, Martin R.; Walton, Richard I.

    2013-11-01

    A new solvothermal synthesis route to mixed-metal gallium oxides with the spinel structure has been developed for ternary oxides of ideal composition Ga3-xMxO4-y (M=Co, Zn, Ni). The structure of the novel cobalt gallate produced in this manner, Ga1.767(8)Co0.973(8)O3.752(8), has been determined from total neutron scattering to be a partially defective spinel with mixed-valent cobalt (approximately 25% Co3+ and 75% Co2+) and with vacancies on approximately 6% of oxygen sites. Pair distribution function (PDF) analysis reveals significant local deviations from the average cubic structure, which are attributed to the conflicting coordination preferences of the Co2+ (potential Jahn-Teller distortion) and Ga3+ (Ga off-centring). Reverse Monte Carlo (RMC) modelling supports this conclusion since different metal-oxygen bond-distance distributions are found for the two cations in the refined configuration. An investigation of magnetic properties shows evidence of short-range magnetic order and spin-glass-like behaviour, consistent with the structural disorder of the material.

  5. Alloy 10: A 1300F Disk Alloy

    NASA Technical Reports Server (NTRS)

    Gayda, John

    2000-01-01

    Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickel-base superalloy disks with 13000 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, Allied Signal's Alloy 10, is a promising candidate for gas turbine engines to be used on smaller, regional aircraft. For this application, compressor/turbine disks must withstand temperatures of 1300 F for several hundred hours over the life of the engine. In this paper, three key properties of Alloy 10--tensile, 0.2% creep, and fatigue crack growth--will be assessed at 1300 F.

  6. Crystal chemistry and self-lubricating properties of monochalcogenides gallium selenide and tin selenide

    SciTech Connect

    Erdemir, A.

    1993-02-01

    This paper describes the fundamentals of the crystal chemistry and self-lubricating mechanisms of two monochalcogenides; tin selenide and gallium selenide. Specifically, it enumerates their inter-atomic array and bond structure in crystalline states, and correlates this fundamental knowledge with their self-lubricating capacity. Friction tests assessing the self-lubricating performance of gallium and tin selenides were carried out on a pin-on-disk machine. Specifically, large crystalline pieces of gallium selenide and tin selenide were cut and cleaved into flat squares and subsequently rubbed against the sapphire balls. In another case, the fine powders (particle size {approx} 50--100 {mu}m) of gallium selenide and tin selenide were manually fed into the sliding interfaces of 440C pins and 440C disks. For the specific test conditions explored, it was found that the friction coefficients of the sapphire/gallium selenide and sapphire/tin selenide pairs were {approx} 0.23 and {approx} 0.35, respectively. The friction coefficients of 440C pin/440C disk test pairs with gallium selenide and tin selenide powders were on the orders of {approx} 0.22 and {approx} 0.38, respectively. For comparison, a number of parallel friction tests were performed with MoS{sub 2} powders and compacts and the results of these tests were also reported. The friction data together with the crystal-chemical knowledge and the electron microscopic evidence supported the conclusion that the lubricity and self-lubricating mechanisms of these solids are closely related to their crystal chemistry and the nature of interlayer bonding.

  7. Aluminum Alloys for High Temperatures

    NASA Technical Reports Server (NTRS)

    Meschter, Peter J.; Lederich, Richard J.; O'Neal, James E.

    1987-01-01

    New Al/Li alloys processed by rapid solidification show greatly improved strength-to-density ratios. Alloys suitable substitutes for heavier titanium alloys and weaker aluminum alloys in high-performance aircraft, bombers, and transports. Also suitable for use in high-performance-aircraft structures heated by engines and normally constructed from titanium alloys.

  8. Calculation of Gallium-metal-Arsenic phase diagrams

    NASA Technical Reports Server (NTRS)

    Scofield, J. D.; Davison, J. E.; Ray, A. E.; Smith, S. R.

    1991-01-01

    Electrical contacts and metallization to GaAs solar cells must survive at high temperatures for several minutes under specific mission scenarios. The determination of which metallizations or alloy systems that are able to withstand extreme thermal excursions with minimum degradation to solar cell performance can be predicted by properly calculated temperature constitution phase diagrams. A method for calculating a ternary diagram and its three constituent binary phase diagrams is briefly outlined and ternary phase diagrams for three Ga-As-X alloy systems are presented. Free energy functions of the liquid and solid phase are approximated by the regular solution theory. Phase diagrams calculated using this method are presented for the Ga-As-Ge and Ga-As-Ag systems.

  9. Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2014-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

  10. Gallium-SPECT in the detection of prosthetic valve endocarditis and aortic ring abscess.

    PubMed

    O'Brien, K; Barnes, D; Martin, R H; Rae, J R

    1991-09-01

    A 52-yr-old man who had a bioprosthetic aortic valve developed Staphylococcus aureus bacteremia. Despite antibiotic therapy he had persistent pyrexia and developed new conduction system disturbances. Echocardiography did not demonstrate vegetations on the valve or an abscess, but gallium scintigraphy using SPECT clearly identified a focus of intense activity in the region of the aortic valve. The presence of valvular vegetations and a septal abscess was confirmed at autopsy. Gallium scintigraphy, using SPECT, provided a useful noninvasive method for the demonstration of endocarditis and the associated valve ring abscess. PMID:1880582

  11. Percolation of gallium dominates the electrical resistance of focused ion beam deposited metals

    SciTech Connect

    Faraby, H. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); DiBattista, M. [Qualcomm Technologies Incorporated, San Diego, California 92121 (United States); Bandaru, P. R., E-mail: pbandaru@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2014-04-28

    Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

  12. Results of the Gallium-Clad Phase 3 and Phase 4 tasks (canceled prior to completion)

    SciTech Connect

    Morris, R.N.

    1998-08-01

    This report summarizes the results of the Gallium-Clad interactions Phase 3 and 4 tasks. Both tasks were to involve examining the out-of-pile stability of residual gallium in short fuel rods with an imposed thermal gradient. The thermal environment was to be created by an electrical heater in the center of the fuel rod and coolant flow on the rod outer cladding. Both tasks were canceled due to difficulties with fuel pellet fabrication, delays in the preparation of the test apparatus, and changes in the Fissile Materials Disposition program budget.

  13. Patterns of gallium-67 scintigraphy in patients with acquired immunodeficiency syndrome and the AIDS related complex

    SciTech Connect

    Bitran, J.; Bekerman, C.; Weinstein, R.; Bennett, C.; Ryo, U.; Pinsky, S.

    1987-07-01

    Thirty-two patients with AIDS related complex (ARC) or acquired immunodeficiency syndrome (AIDS) underwent /sup 67/Ga scans as part of their evaluation. Three patterns of /sup 67/Ga biodistribution were found: lymph node uptake alone; diffuse pulmonary uptake; normal scan. Gallium-67 scans were useful in identifying clinically occult Pneumocystis carinii pneumonia in seven of 15 patients with ARC who were asymptomatic and had normal chest radiographs. Gallium scans are a useful ancillary procedure in the evaluation of patients with ARC or AIDS.

  14. Gallium-SPECT in the detection of prosthetic valve endocarditis and aortic ring abscess

    SciTech Connect

    O'Brien, K.; Barnes, D.; Martin, R.H.; Rae, J.R. (Department of Diagnostic Radiology, Victoria General Hospital Halifax, Nova Scotia (Canada))

    1991-09-01

    A 52-yr-old man who had a bioprosthetic aortic valve developed Staphylococcus aureus bacteremia. Despite antibiotic therapy he had persistent pyrexia and developed new conduction system disturbances. Echocardiography did not demonstrate vegetations on the valve or an abscess, but gallium scintigraphy using SPECT clearly identified a focus of intense activity in the region of the aortic valve. The presence of valvular vegetations and a septal abscess was confirmed at autopsy. Gallium scintigraphy, using SPECT, provided a useful noninvasive method for the demonstration of endocarditis and the associated valve ring abscess.

  15. Growth of epitaxial bismuth and gallium substituted lutetium iron garnet films by pulsed laser deposition

    SciTech Connect

    Leitenmeier, Stephan; Heinrich, Andreas; Lindner, Joerg K. N.; Stritzker, Bernd [Institut fuer Physik, Universitaet Augsburg, D-86135 Augsburg (Germany)

    2006-04-15

    Epitaxial bismuth and gallium substituted lutetium iron garnet thin films have been grown on (100) oriented gadolinium gallium garnet Gd{sub 3}Ga{sub 5}O{sub 12} substrates by pulsed laser deposition. The films have been studied using x-ray diffraction, high resolution x-ray diffraction, Rutherford backscattering spectroscopy, transmission electron microscopy, and electron diffraction. We obtained smooth films with thicknesses between 0.3 and 1.0 {mu}m showing good crystalline quality and epitaxial growth.

  16. Effect of magnetic field on the mechanical properties of magnetostrictive iron-gallium nanowires

    SciTech Connect

    Downey, Patrick R.; Flatau, Alison B. [Department of Aerospace Engineering, University of Maryland, 3181 Martin Hall, College Park, Maryland 20742 (United States); McGary, Patrick D.; Stadler, Bethanie J. H. [Department of Electrical and Computer Engineering, University of Minnesota, 200 Union St., Minneapolis, Minnesota 55455 (United States)

    2008-04-01

    This study experimentally investigates the elastic properties of individual iron-gallium nanowires with and without an applied magnetic bias field. The experiments were conducted with a custom manipulator stage designed for use within a scanning electron microscope, where nanowires were mechanically tested both statically and dynamically. Experiments were also performed in the presence of a 20 Oe dc magnetic field in order to identify any variation in wire properties. The results suggest that iron-gallium nanowires possess an elastic modulus very similar to the macroscale value, tensile strengths of more than double the bulk material, and minor magnetic field induced stiffening at low stresses.

  17. 3D structures of liquid-phase GaIn alloy embedded in PDMS with freeze casting.

    PubMed

    Fassler, Andrew; Majidi, Carmel

    2013-11-21

    Liquid phase electronic circuits are created by freeze casting gallium-indium (GaIn) alloys, such as eutectic gallium-indium (EGaIn), and encapsulating these frozen components within an elastomer. These metal alloys are liquid at room temperature, and can be cast using either injection or a vacuum to fill a PDMS mold and placing the mold in a freezer. Once solidified, a GaIn alloy segment can be manipulated, altered, or bonded to other circuit elements. A stretchable circuit can be fabricated by placing frozen components onto an elastomer substrate, which can be either patterned or flat, and sealing with an additional layer of elastomer. Circuits produced in this fashion are soft, stretchable, and can have complex 3D channel geometries. In contrast, current fabrication techniques, including needle injection, mask deposition, and microcontact printing, are limited to 2D planar designs. Additionally, freeze casting fabrication can create closed loops, multi-terminal circuits with branching features, and large area geometries. PMID:24067934

  18. Synthesis and characterisation of chromium lutetium gallium garnet solid solution

    SciTech Connect

    Galindo, R. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Badenes, J.A. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain)]. E-mail: jbadenes@qio.uji.es; Llusar, M. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Tena, M.A. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain); Monros, G. [Inorganic Chemistry Area, Inorganic and Organic Department, Jaume I University, Castellon 12071 (Spain)

    2007-03-22

    The chromium lutetium gallium garnet system has been studied. Samples with 2xCaOxCr{sub 2}O{sub 3}(3 - 2x)Lu{sub 2}O{sub 3}5Ga{sub 2}O{sub 3} (x = 0.025, 0.05, 0.075, 0.1, 0.2 and 0.3,) and xCr{sub 2}O{sub 3}(3 - x)Lu{sub 2}O{sub 3}5Ga{sub 2}O{sub 3} (x = 0, 0.05, 0.075 and 0.3) compositions have been prepared in Ca,Cr:LGG and Cr:LGG systems, respectively. Samples were prepared by ceramic method, fired at 1250 deg. C/6 h and characterised by XRD, lattice parameters, UV-vis-NIR spectroscopy, CIE L * a * b * measurements and SEM/EDX. Results indicate that Ca,Cr:LGG and Cr:LGG solid solutions are obtained. In Cr:LGG system only Cr(III) is stabilised in octahedral positions substituting for Lu(III) and Ga(III). Both Cr(III) and Cr(IV) are present in Ca,Cr:LGG. The calcium is a charge compensator to stabilise Cr(IV) and this is the predominant oxidation state up to x = 0.075 composition. From this composition, Cr(III) becomes more stabilised in garnet lattice. Cr(IV) occupies generally tetrahedral and dodecahedral sites substituting for Ga(III) and Lu(III), while Cr(III) is in octahedral site substituting for Ga(III)

  19. Supersonic jet epitaxy of gallium nitride using triethylgallium and ammonia

    NASA Astrophysics Data System (ADS)

    McGinnis, Arthur J.; Thomson, Darren; Banks, Andrew; Preble, Edward; Davis, Robert F.; Lamb, H. Henry

    2003-01-01

    Gallium nitride (GaN) films were grown on GaN(0001)/AlN/6H-SiC composite substrates at 700-780 °C by supersonic jet epitaxy using triethylgallium (TEG) and NH3. TEG was seeded in He and N2 supersonic free jets to obtain kinetic energies of ~2.1 and ~0.5 eV, respectively, and NH3 was supplied from a variable leak valve. Higher TEG beam intensities (by about a factor of 5) were obtained by seeding in He. In situ reflection high-energy electron diffraction indicated a transition from three-dimensional to two-dimensional (2D) growth between 730 and 750 °C for films grown using TEG seeded in He and a constant NH3/TEG flux ratio. Ex situ atomic force microscopy of films grown at 730 and 750 °C revealed smooth surfaces comprised of quasi-2D islands with irregular perimeters. Cross-sectional transmission electron microscopy evidenced that the film grown at 750 °C was homoepitaxial ?-GaN with a high density of planar lattice defects. Secondary ion mass spectrometry detected high residual carbon concentrations in the films. The GaN growth rate at 750 °C was found to depend on TEG flux and NH3 pressure in a manner consistent with Langmuir-Hinshelwood kinetics. Films grown under NH3-rich conditions were faceted and microscopically rough, whereas nonfaceted, basal-plane growth was observed under Ga-rich conditions. The first-order dependence of growth rate on TEG flux under NH3-rich conditions was used to estimate Ga incorporation efficiencies for high- and low-energy TEG beams. The Ga incorporation efficiency is lower for high-energy TEG beams, consistent with a decrease in the sticking coefficient for dissociative chemisorption.

  20. Millimeter wave ferromagnetic resonance in gallium-substituted ?-iron oxide

    SciTech Connect

    Chao, Liu, E-mail: liu.chao@tufts.edu; Afsar, Mohammed N. [Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States); Ohkoshi, Shin-ichi [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2014-05-07

    In millimeter wave frequency range, hexagonal ferrites with high uniaxial anisotropic magnetic fields are used as absorbers. These ferrites include M-type barium ferrite (BaFe{sub 12}O{sub 19}) and strontium ferrite (SrFe{sub 12}O{sub 19}), which have natural ferromagnetic resonant frequency range from 40 GHz to 60?GHz. However, the higher frequency range lacks suitable materials that support the higher frequency ferromagnetic resonance. A new series of gallium-substituted ?-iron oxides (?-Ga{sub x}Fe{sub 2?x}O{sub 3}) are synthesized which have ferromagnetic resonant frequencies appearing over the frequency range 30 GHz–150 GHz. The ?-Ga{sub x}Fe{sub 2?x}O{sub 3} is synthesized by the combination of reverse micelle and sol-gel techniques or the sol-gel method only. The particle sizes are observed to be smaller than 100 nm. In this paper, the free space magneto-optical approach has been employed to study these newly developed ?-Ga{sub x}Fe{sub 2?x}O{sub 3} particles in millimeter waves. This technique enables to obtain precise transmission spectra to determine the dielectric and magnetic properties of both isotropic and anisotropic ferrites in the millimeter wave frequency range from a single set of direct measurements. The transmittance and absorbance spectra of ?-Ga{sub x}Fe{sub 2?x}O{sub 3} are shown in this paper. Strong ferromagnetic resonances at different frequencies determined by the x parameter are found.

  1. Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.

    2005-01-01

    Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

  2. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  3. Low activation ferritic alloys

    DOEpatents

    Gelles, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  4. Low activation ferritic alloys

    DOEpatents

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  5. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  6. Ferromagnetic bulk amorphous alloys

    Microsoft Academic Search

    Akihisa Inoue; Akira Takeuchi; Tao Zhang

    1998-01-01

    This article reviews our recent results on the development of ferromagnetic bulk amorphous alloys prepared by casting processes.\\u000a The multicomponent Fe-(Al,Ga)-(P,C,B,Si) alloys are amorphized in the bulk form with diameters up to 2 mm, and the temperature\\u000a interval of the supercooled liquid region before crystallization is in the range of 50 to 67 K. These bulk amorphous alloys\\u000a exhibit good

  7. Group 13 ligand supported heavy-metal complexes: first structural evidence for gallium-lead and gallium-mercury bonds.

    PubMed

    Prabusankar, Ganesan; Gemel, Christian; Winter, Manuela; Seidel, Rüdiger W; Fischer, Roland A

    2010-05-25

    Heavy-metal complexes of lead and mercury stabilized by Group 13 ligands were derived from the oxidative addition of Ga(ddp) (ddp=HC(CMeNC(6)H(3)-2,6-iPr(2))(2), 2-diisopropylphenylamino-4-diisopropyl phenylimino-2-pentene) with corresponding metal precursors. The reaction of Me(3)PbCl and Ga(ddp) afforded compound [{(ddp)Ga(Cl)}PbMe(3)] (1) composed of Ga-Pb(IV) bonds. In addition, the monomeric plumbylene-type compound [{(ddp)Ga(OSO(2)CF(3))}(2)Pb(thf)] (2a) with an unsupported Ga-Pb(II)-Ga linkage was obtained by the reaction of [Pb(OSO(2)CF(3))(3)] with Ga(ddp) (2 equiv). Compound 2a falls under the rare example of a discrete plumbylene-type compound supported by a nonclassical ligand. Interesting structural changes were observed when [Pb(OSO(2)CF(3))(3)]2.H(2)O was treated with Ga(ddp) in a 1:2 ratio to yield [{(ddp)Ga(mu-OSO(2)CF(3))}(2)(OH(2))Pb] (2b) at below -10 degrees C. Compound 2b consists of a bent Ga-Pb-Ga backbone with a bridging triflate group between the Ga-Pb bond and a weakly interacting water molecule at the gallium center. Similarly, the reaction of mercury thiolate Hg(SC(6)F(5)) with Ga(ddp) (2 equiv) produced the bimetallic homoleptic compounds anti-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3a) and gauche-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3b), respectively, with a linear Ga-Hg-Ga linkage. Compounds 1-3 were structurally characterized and these are the first examples of compounds comprised of Ga-Pb(II), Ga-Pb(IV), and Ga-Hg bonds. PMID:20391574

  8. Metal contacts to gallium nitride J. S. Foresi and T. D. Moustakas

    E-print Network

    Moustakas, Theodore

    Metal contacts to gallium nitride J. S. Foresi and T. D. Moustakas Molecular Beam Epitaxy on the nature of aluminum and gold contacts to GaN. The GaN films were deposited onto the R-plane of sapphire substrates by molecular beam epitaxy and are autodoped n-type. Metal contacts were deposited by evaporation

  9. Gallium-rich reconstructions on GaAs(001) M. Pristovsek*; 1

    E-print Network

    Schmidt, Wolf Gero

    - tion High-Energy Electron Diffraction. Annealing or dosing gallium above about 800 K invariably re. Koguchi1 , B. G. Orr2 , W. G. Schmidt3 , and J. Bernholc3 1 Nano-Device Research Group, National Institute of Molecular Beam Epitaxy grown samples and analyzed in-situ by Reflectance Anisotropy Spectroscopy and Reflec

  10. Layer by layer nanoassembly of copper indium gallium selenium (CIGS) nanoparticles for solar cell application

    Microsoft Academic Search

    Azadeh Hemati

    2011-01-01

    In this research thesis, copper indium gallium selenium (CIGS) nanoparticles were synthesized from metal chlorides, functionalized to disperse in water, and further used in layer by layer (LbL) nanoassembly of CIGS films. CIGS nanoparticles were synthesized through the colloidal precipitation in an organic solvent. The peak and average sizes of the synthesized particles were measured to be 68 nm and

  11. Gallium citrate Ga 67 accumulation in pulmonary lesions after chemotherapy (MOPP)

    SciTech Connect

    Wells, J.D.; Huskison, W.T.; Davenport, O.L.

    1986-10-01

    We have described a patient with Hodgkin's disease who had fever and pulmonary infiltrates after treatment with mantle x-ray therapy and two courses of MOPP. Gallium affinity of the lung lesions proved at biopsy not to be due to Hodgkin's disease, but probably to chemotherapy-induced pulmonary toxicity.

  12. Role of iron-binding proteins and enhanced capillary permeability on the accumulation of gallium-67

    SciTech Connect

    Tzen, K.Y.; Oster, Z.H.; Wagner, H.N. Jr.; Tsan, M.F.

    1980-01-01

    We studied the role of the iron-binding proteins transferrin and lactoferrin and of increased capillary permeability on the accumulation of gallium-67 in rabbits. Intramuscular injection of histamine caused accumulation of gallium-67 (injected iv as citrate), and of Tc-99m DTPA, at the im injection site. Normal saline and albumin did not. Intramuscular injection of transferrin or lactoferrin similarly caused Ga-67 uptake. No accumulation of Tc-99m DTPA was observed at the site of transferrin injection but there was a slight accumulation at the site of lactoferrin injection. Prior saturation of transferrin or lactoferrin with ferric ion abolished their effect on Ga-67 accmulation. Gallium-67, pre-bound to transferrin in vitro, did not accumulate at the site of histamine or transferrin injection, but there was a slight accumulation at the lactoferrin site. Our results suggest that either increased capillary permeability of iron-binding proteins can cause local uptake of Ga-67. Since these factors are present at sites of inflammation, they may contribute to the accumulation of gallium in inflammatory lesions.

  13. Investigation of the surface state of semi-insulating gallium arsenide after high-temperature annealing

    Microsoft Academic Search

    N. I. Kurdiani; O. O. Gachechiladze; A. A. Mirtskhulava; Z. A. Adamiya; B. G. Eristavi

    1988-01-01

    The distribution of chromium and silicon in near-surface domains of semi-insulating gallium arsenide after annealing at different temperatures is investigated by the secondary ion method. It is shown that the surface of the specimens investigated is concentrated with the elements mentioned as a result of the annealing, however, their distribution over the bulk is not monotonie in nature. A considerably

  14. Influence of various factors on the accuracy of gallium-67 imaging for occult infection

    SciTech Connect

    Maderazo, E.G.; Hickingbotham, N.B.; Woronick, C.L.; Sziklas, J.J.

    1988-05-01

    To examine whether the results and interpretation of gallium-67 citrate imaging may be adversely influenced by factors present in compromised patients, we reviewed our 1-year experience in 69 patients in intensive care units, renal transplants, and those on hemodialysis. Our results indicate that it is an inappropriate diagnostic procedure for acute pancreatitis since seven of nine had false-negative results. Using loglinear modeling and chi-square analysis we found that treatment with antiinflammatory steroids, severe liver disease, end-stage renal disease, and renal transplantation with immunosuppressive therapy did not interfere with gallium-67 uptake. Increased rate of true-negative results in patients with end-stage renal disease was due to a greater and earlier use of the test in the febrile transplant patient and in hemodialysis patients with infections not amenable to diagnosis with gallium-67 scan (transient bacteremia and bacteriuria). We conclude that gallium-67 imaging is a useful diagnostic tool that, with the exception of acute pancreatitis, has very few false-negative results.

  15. Damage formed by electron cyclotron resonance plasma etching on a gallium arsenide surface

    Microsoft Academic Search

    Tohru Hara; Jun Hiyoshi; Hiromi Hamanaka; Masami Sasaki; Fukuya Kobayashi; Katsumi Ukai; Takashi Okada

    1990-01-01

    Radiation damage induced on a gallium arsenide surface by electron cyclotron resonance (ECR) plasma etching is studied. The number of displaced atoms (displaced atom density) formed by exposure to ECR plasma is determined quantitatively by Rutherford backscattering spectrometry aligned spectra. The density increases with increasing microwave power. The amount of increase of displaced atom density from the undamaged virgin surface

  16. ELECTRON MICROPROBE AND PHOTOLUMINESCENCE ANALYSIS OF EUROPIUM-DOPED GALLIUM NITRIDE LIGHT EMITTERS

    E-print Network

    Strathclyde, University of

    ELECTRON MICROPROBE AND PHOTOLUMINESCENCE ANALYSIS OF EUROPIUM-DOPED GALLIUM NITRIDE LIGHT EMITTERSN-on-sapphire epilayers implanted with Europium ions, producing characteristic red emission lines between 540 and 680 nm with energies largely independent of the host material. For example, doping with europium, erbium and thulium

  17. Crystal chemistry and solid lubricating properties of the monochalcogenides gallium selenide and tin selenide

    NASA Astrophysics Data System (ADS)

    Erdemir, Ali

    1994-07-01

    The interatomic array and bond structure in crystalline states of the monochalcogenides tin selenide and gallium selenide are described and correlated with their solid lubricating capacity. Friction tests assessing their solid lubricating performance were carried out on pin-on-disk machine. Specifically, large crystalline pieces of each inorganic solid were cut and cleaved into flat squares and subsequently rubbed against sapphire balls. In another case, fine powders of gallium selenide and tin selenide and tin selenide were manually fed into the sliding interfaces of 440C pins and 440C disks. For the specific test conditions explored, friction coefficients of the sapphirel gallium selenide and sapphire/tin selenide pairs were approximately 0.23 and approximately 0.35, respectively. The friction coefficients of 440C pin/440C disk test pairs with gallium selenide and tin selenide powders were approximately 0.22 and approximately 0.38, respectively. For comparison, a number of parallel friction tests were also performed with MoS2 powders and compacts, and the results of these tests are reported. The friction data, together with the crystal-chemical knowledge and electron microscopy evidence, supported the conclusion that the solid lubricating capabilities and lubrication mechanisms of these solids are closely related to their crystal chemistry and the nature of their interlayer bonding.

  18. Gallium Oxide Nanoribbons and Nanosheets Z. R. Dai, Z. W. Pan, and Z. L. Wang*

    E-print Network

    Wang, Zhong L.

    . Gallium oxide is an important functional material. It has been used as insulating barrier for spin of an alumina tube that was inserted in a horizontal tube furnace. The furnace was heated at a rate of 10-15 °C, the products were deposited onto polycrystalline alumina plates placed at the downstream end of the alumina

  19. Skylab experiment performance evaluation manual. Appendix J: Experiment M555 gallium arsenide single crystal growth (MSFC)

    NASA Technical Reports Server (NTRS)

    Byers, M. S.

    1973-01-01

    Analyses for Experiment M555, Gallium Arsenide Single Crystal Growth (MSFC), to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and post-flight conditions are presented. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful.

  20. Gallium arsenide integrated optical devices for high-speed diagnostic systems

    SciTech Connect

    McWright, G.; Lowry, M.; Takeuchi, E.; Murphy, G.; Tindall, W.; Koo, J.; Roeske, F.

    1987-01-01

    The design, fabrication, and evaluation of waveguide electro-optic modulators in gallium arsenide for application to high-speed diagnostic systems are discussed specifically. This paper is focused on high bandwidth, single event analog modulation, and radiation susceptibility of these devices.

  1. Epitaxial growth of ferromagnetic -phase manganese gallium on semiconducting scandium nitride (001)

    E-print Network

    Ga//[100]ScN . Vibrating sample magnetometry measurements indicate out-of-plane magnetization of the film, suggesting strong magnetic anisotropy along the manganese gallium c-axis. PACS numbers: 68.55.A-, 75.30.Gw.edu 1 #12;I. INTRODUCTION Ferromagnetic thin films on semiconductor bi-layer structures have attracted

  2. Cationic ring-opening polymerization of tetrahydrofuran with boron, aluminium, and gallium tristriflate

    SciTech Connect

    Olah, G.A.; Farooq, O.; Li, C.H.; Farnia, M.A.M.; Aklonis, A. (University of Southern California, Los Angeles, CA (United States). Dept. of Chemistry)

    1992-07-25

    Boron, aluminum, and gallium tristriflate are new effective catalysts for the polymerization of tetrahydrofuran (THF). High-molecular-weight polytetrahydrofuran (PTHF) obtained in excellent yield in the bulk polymerization of THF at ambient temperature with all three catalysts. The PTHF samples are characterized and some of their thermodynamic and mechanical properties are investigated and discussed in this paper.

  3. Bilateral Comparison of Mercury and Gallium Fixed-Point Cells Using Standard Platinum Resistance Thermometer

    NASA Astrophysics Data System (ADS)

    Bojkovski, J.; Veliki, T.; Zvizdi?, D.; Drnovšek, J.

    2011-08-01

    The objective of project EURAMET 1127 (Bilateral comparison of triple point of mercury and melting point of gallium) in the field of thermometry is to compare realization of a triple point of mercury (-38.8344 °C) and melting point of gallium (29.7646 °C) between the Slovenian national laboratory MIRS/UL-FE/LMK and the Croatian national laboratory HMI/FSB-LPM using a long-stem 25 ? standard platinum resistance thermometer (SPRT). MIRS/UL/FE-LMK participated in a number of intercomparisons on the level of EURAMET. On the other hand, the HMI/LPM-FSB laboratory recently acquired new fixed-point cells which had to be evaluated in the process of intercomparisons. A quartz-sheathed SPRT has been selected and calibrated at HMI/LPM-FSB at the triple point of mercury, the melting point of gallium, and the water triple point. A second set of measurements was made at MIRS/UL/FE-LMK. After its return, the SPRT was again recalibrated at HMI/LPM-FSB. In the comparison, the W value of the SPRT has been used. Results of the bilateral intercomparison confirmed that the new gallium cell of the HMI/LPM-FSB has a value that is within uncertainty limits of both laboratories that participated in the exercise, while the mercury cell experienced problems. After further research, a small leakage in the mercury fixed-point cell has been found.

  4. Functionalization of nitrogen-doped carbon nanotubes with gallium to form Ga-CNx-multi-wall carbon nanotube hybrid materials

    NASA Astrophysics Data System (ADS)

    Simmons, Trevor J.; Hashim, Daniel P.; Zhan, Xiaobo; Bravo-Sanchez, Mariela; Hahm, Myung Gwan; López-Luna, Edgar; Linhardt, Robert J.; Ajayan, Pulickel M.; Navarro-Contreras, Hugo; Vidal, Miguel A.

    2012-08-01

    In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI3), it was possible to form covalent bonds between the Ga3+ ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy

  5. Three cases demonstrating the role of gallium scanning in relapsing Hodgkin's disease and non-Hodgkin lymphoma

    SciTech Connect

    Zollars, L.E.; Nagel, J.S.; Tumeh, S.S.

    1987-10-01

    Restaging of Hodgkin's disease and non-Hodgkin lymphoma for chemotherapy traditionally requires chest radiograph and abdominal computerized tomogram (CT) for routine follow-up examination. Although gallium scanning has had a poor record in the past, recent studies suggest that improved techniques have given this method high sensitivity. We present three cases in which gallium correctly staged lymphoma that had been missed or misinterpreted by chest radiographs and abdominal CT. Gallium imaging is useful in follow-up of lymphoma patients especially when the CT scan is difficult to interpret.

  6. Deposition and characterization of amorphous gallium nitride thin films

    NASA Astrophysics Data System (ADS)

    Kang, Yixiu

    Theoretical study by Stumm and Drabold [P. Stumm and D. A. Drabold, Phys. Rev. Lett 79, 677 (1997)] showed that amorphous GaN could be a promising wide bandgap semiconductor material for electronic and optoelectronic device applications. In this dissertation, a-GaN and a-GaN:Er thin films were prepared by means of ion beam assisted evaporation at room temperature in an ultra-high vacuum chamber. The properties of as-deposited and thermal annealed films were studied by a variety of characterization methods. X-ray diffraction, electron diffraction, and Raman spectroscopy results confirmed that the films are amorphous. Depending on the deposition condition, films with Ga to N ratio of 1.0:0.5 to 1.0:1.4 were obtained. The film with the Ga:N ratio of 1.0:1.3 +/- 0.1 has an optical bandgap of ˜2.5eV measured at the absorption coefficient of 104cm-1 , whereas the optical bandgap is ˜2.0eV from a Tauc plot. The film is highly transparent for light with energy lower than the bandgap energy, while gallium rich films showed much higher absorption in the same region, which indicate that a clean band gap can be obtained for a-GaN film by preparing nitrogen rich films. Oxidation at room temperature has been observed for some films, while others are stable against oxidation until annealed above 500°C. The densities of the a-GaN and a-GaN:O films in this work are 62 to 78 at % and 68 to 85 at respectively, of that of crystalline GaN, and the more the N or N+O in the film, the lower the density of the film. XPS and AES results showed that the binding energies for N and Ga to be consisted with Ga-N bonding. The XPS valence band spectrum showed that the highest valence band state is about 1.5eV below the Fermi level. Both as-deposited and annealed (at 900°C in N2) a-GaN:Er film showed IR emissions in the range of 950--1000nm by PL measurement. The annealed film also showed visible emissions near 700nm by PL measurement.

  7. Preconceptual design for separation of plutonium and gallium by ion exchange

    SciTech Connect

    DeMuth, S.F.

    1997-09-30

    The disposition of plutonium from decommissioned nuclear weapons, by incorporation into commercial UO{sub 2}-based nuclear reactor fuel, is a viable means to reduce the potential for theft of excess plutonium. This fuel, which would be a combination of plutonium oxide and uranium oxide, is referred to as a mixed oxide (MOX). Following power generation in commercial reactors with this fuel, the remaining plutonium would become mixed with highly radioactive fission products in a spent fuel assembly. The radioactivity, complex chemical composition, and large size of this spent fuel assembly, would make theft difficult with elaborate chemical processing required for plutonium recovery. In fabricating the MOX fuel, it is important to maintain current commercial fuel purity specifications. While impurities from the weapons plutonium may or may not have a detrimental affect on the fuel fabrication or fuel/cladding performance, certifying the effect as insignificant could be more costly than purification. Two primary concerns have been raised with regard to the gallium impurity: (1) gallium vaporization during fuel sintering may adversely affect the MOX fuel fabrication process, and (2) gallium vaporization during reactor operation may adversely affect the fuel cladding performance. Consequently, processes for the separation of plutonium from gallium are currently being developed and/or designed. In particular, two separation processes are being considered: (1) a developmental, potentially lower cost and lower waste, thermal vaporization process following PuO{sub 2} powder preparation, and (2) an off-the-shelf, potentially higher cost and higher waste, aqueous-based ion exchange (IX) process. While it is planned to use the thermal vaporization process should its development prove successful, IX has been recommended as a backup process. This report presents a preconceptual design with material balances for separation of plutonium from gallium by IX.

  8. Shape Memory Alloys

    Microsoft Academic Search

    Abhijit Bhattacharyya; Dimitris C Lagoudas

    2007-01-01

    This special issue on shape memory alloys (SMA) is an encore to a special issue on the same topic edited by us six years ago (Smart Mater. Struct.9 (5) October 2000). A total of 19 papers is offered in this issue, organized into the three broad categories of modeling, characterization and applications. In addition to thermally activated shape memory alloys,

  9. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  10. Cesium iodide alloys

    DOEpatents

    Kim, H.E.; Moorhead, A.J.

    1992-12-15

    A transparent, strong CsI alloy is described having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy with outstanding multispectral infrared transmittance properties. 6 figs.

  11. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A. (Ames, IA); Verhoeven, John D. (Ames, IA); Gibson, Edwin D. (Ames, IA)

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  12. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V. (Boulder, CO)

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  13. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E. (Idaho Falls, ID); Shaber, Eric L. (Idaho Falls, ID); DuPont, John N. (Whitehall, PA); Robino, Charles V. (Albuquerque, NM); Williams, David B. (Bethlehem, PA)

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  14. Alloys for aerospace

    SciTech Connect

    Tuominen, S.; Wojcik, C. [Teledyne Wah Chang, Albany, OR (United States)

    1995-04-01

    Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys are prepared by vacuum-arc-remelting (VAR) or electron beam (EB) melting, and ingots are processed to products ranging from bar and tube stock to wire and foil. Chemical, mechanical, and microstructural tests are all conducted at TWC`s in-house laboratory facilities. Of the alloys described here, Ti-3Al-2.5V, Tiadyne 3515 (Alloy C), NiTiFe, and C-103 are produced commercially, while orthorhombic titanium aluminides are promising candidates for future light-weight composite matrices.

  15. Dual alloy interface stability

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1982-01-01

    Powder metallurgy dual alloy fabrication is applied to combinations of superalloys having a high iron, and low strategic metal content, with standard nickel base superalloys, containing the strategic metals chromium, cobalt, and columbium. The possibility of combining Alloy 901 (12 percent Cr, 36 percent Fe, 0 percent Co, and 0 percent Cb) with turbine disk alloys Rene 95 (13 percent Cr, 8 percent Co, and 4 percent Cb) or low carbon astroloy (L.C.A.; 15 percent Cr, 17 percent Co, and 0 percent Cb) is investigated. Preliminary results for combinations show that a strong interface with rapid diffusion is obtained between alloys and that the standard heat treatments for either alloy may be satisfactory.

  16. Structure and Properties of Epitaxial Dielectrics on gallium nitride

    NASA Astrophysics Data System (ADS)

    Wheeler, Virginia Danielle

    GaN is recognized as a possible material for metal oxide semiconductor field effect transistors (MOSFETs) used in high temperature, high power and high speed electronic applications. However, high gate leakage and low device breakdown voltages limit their use in these applications. The use of high-kappa dielectrics, which have both a high permittivity (?) and high band gap energy (Eg), can reduce the leakage current density that adversely affects MOS devices. La2O3 and Sc2O 3 are rare earth oxides with a large Eg (6.18 eV and 6.3 eV respectively) and a relatively high ? (27 and 14.1 respectively), which make them good candidates for enhancing MOSFET performance. Epitaxial growth of oxides is a possible approach to reducing leakage current and Fermi level pinning related to a high density of interface states for dielectrics on compound semiconductors. In this work, La2O3 and Sc2O 3 were characterized structurally and electronically as potential epitaxial gate dielectrics for use in GaN based MOSFETs. GaN surface treatments were examined as a means for additional interface passivation and influencing subsequent oxide formation. Potassium persulfate (K2(SO4)2) and potassium hydroxide (KOH) were explored as a way to achieve improved passivation and desired surface termination for GaN films deposited on sapphire substrates by metal organic chemical vapor deposition (MOCVD). X-ray photoelectron spectroscopy (XPS) showed that KOH left a nitrogen-rich interface, while K2(SO 4)2 left a gallium-rich interface, which provides a way to control surface oxide formation. K2(SO4)2 exhibited a shift in the O1s peak indicating the formation of a gallium-rich GaOx at the surface with decreased carbon contaminants. GaO x acts as a passivating layer prior to dielectric deposition, which resulted in an order of magnitude reduction in leakage current, a reduced hysteresis window, and an overall improvement in device performance. Furthermore, K2(SO4)2 resulted in an additional 0.4 eV of upward band bending at the surface, which should be considered when determining heterojunction band offsets with GaN. Epitaxial La2O3 and Sc2O3 were successfully deposited on GaN by molecular beam epitaxy (MBE). Sc 2O3 exhibited a cubic bixbyite crystal structure, while La 2O3 had a mix of both cubic and hexagonal crystal structures. A highly defective structure was observed for La2O3, compared to Sc2O3, which results from its larger mismatch with GaN (14.5% and 8.9%, respectively). TEM images indicated an abrupt atomic interface for Sc2O3 films, but an interfacial layer was observed for La2O3 on GaN. Additionally, La 2O3 was shown to be extremely reactive with water and carbon dioxide in air, forming both hydroxides and carbonates within 15 minutes of exposure. Therefore, tantalum and silicon were investigated as in-situ capping metals to prevent these deleterious effects. XPS was utilized to determine a valence band offset (VBO) and conduction band offset of 1.9 +/- 0.1 eV and 0.9 +/- 0.1 eV for La2O 3 on GaN. Similarly, Sc2O3 had a VBO and CBO of 0.8 +/- 0.1 eV and 2.1 +/- 0.1 eV, respectively. Both oxides exhibited sufficient band offsets to prevent thermionic emission of carriers, even at high operation temperatures, making them good candidates for insulator layers in high temperature, high power applications. Preliminary C-V curves, for La2O3 and Sc2 O3 MOS capacitors, showed large charge accumulation layers, extremely high permittivity values, and low hysteresis windows indicative of low density of interface traps and fixed oxide charges. I-V curves showed a reduction in leakage current density for both oxides compared to Si 3N4, a readily used gate dielectric for GaN devices. The larger reduction achieved with La2O3 films is attributed to a passivating interfacial layer that minimizes the amount of dislocations propagating into the oxide. These preliminary results point to the viability of these gate oxides in GaN MOSFET devices.

  17. High temperature ultrasonic transducers for imaging and measurements in a liquid Pb/Bi eutectic alloy.

    PubMed

    Kazys, Rymantas; Voleisis, Algirdas; Sliteris, Reimondas; Mazeika, Liudas; Van Nieuwenhove, Rudi; Kupschus, Peter; Abderrahim, Hamid Aït

    2005-04-01

    In some nuclear reactors or accelerator-driven systems (ADS) the core is intended to be cooled by means of a heavy liquid metal, for example, lead-bismuth (Pb/Bi) eutectic alloy. For safety and licensing reasons, an imaging method of the interior of ADS, based on application of ultrasonic waves, has thus to be developed. This paper is devoted to description of developed various ultrasonic transducers suitable for long term imaging and measurements in the liquid Pb/Bi alloy. The results of comparative experimental investigations of the developed transducers of different designs in a liquid Pb/Bi alloy up to 450 degrees C are presented. Prototypes with different high temperature piezoelectric materials were investigated: PZT, bismuth titanate (Bi4Ti3O12), lithium niobate (LiNbO3), gallium orthophosphate (GaPO4) and aluminum nitride (A1N). For acoustic coupling with the metal alloy, it was proposed to coat the active surface of the transducers by diamond like carbon (DLC). The radiation robustness was assessed by exposing the transducers to high gamma dose rates in one of the irradiation facilities at SCK x CEN. The experimental results proved that the developed transducers are suitable for long-term operation in harsh conditions. PMID:16060499

  18. Magnetostriction of ternary Fe -Ga-X (X=C,V,Cr,Mn,Co,Rh) alloys

    NASA Astrophysics Data System (ADS)

    Clark, A. E.; Restorff, J. B.; Wun-Fogle, M.; Hathaway, K. B.; Lograsso, T. A.; Huang, M.; Summers, E.

    2007-05-01

    Binary iron-gallium (Galfenol) alloys have large magnetostrictions over a wide temperature range. Single crystal measurements show that additions of 2at.% or greater of 3d and 4d transition elements with fewer (V, Cr, Mo, Mn) and more (Co, Ni, Rh) valence electrons than Fe, all reduce the saturation magnetostriction. Kawamiya and Adachi [J. Magn. Magn. Mater. 31-34, 145 (1983)] reported that the D03 structure is stabilized by 3d transition elements with electron/atom ratios both less than iron and greater than iron. If D03 ordering decreases the magnetostriction, the maximum magnetostriction should be largest for the (more disordered) binary Fe-Ga alloys as observed. Notably, addition of small amounts of C (0.07, 0.08, and 0.14at.%) increases the magnetostriction of the slow cooled binary alloy to values comparable to the rapidly quenched alloy. We assume that small atom (C, B, N) additions enter interstitially and inhibit ordering, thus maximizing the magnetostriction without quenching.

  19. The value of Tc99m (V) dimercaptosuccinic acid in detecting intra-abdominal infection: compared with gallium scan

    Microsoft Academic Search

    Wan-Yu Lin; Guang-Uei Hung; Te-Hsin Chao

    2007-01-01

    Objective  Gallium-67 (Ga-67) and labeled leukocytes are useful in the detection of an unknown infectious source. However, the delay\\u000a in the diagnosis of a Ga-67 citrate scan (gallium scan) and the complicated labeling technique of a leukocyte scan are major\\u000a drawbacks to their clinical use. Recently, Tc-99m (V) dimercaptosuccinic acid (DMSA) has been found to be very useful in the\\u000a detection

  20. Separation and recovery of gallium and indium from simulated zinc refinery residue by liquid-liquid extraction

    Microsoft Academic Search

    Syouhei Nishihama; Takayuki Hirai; Isao Komasawa

    1999-01-01

    The separation and recovery of gallium and indium from zinc refinery residue, using liquid-liquid extraction, has been investigated. The major components with the exception of zinc can be removed by extraction with tri-n-butyl phosphate at low aqueous acidity, and gallium and indium can be separated from the remaining major component, zinc, by extraction with bis(2-ethylhexyl)phosphoric acid (D2EHPA) using the correct

  1. The 13.9 GHz short pulse radar noise figure measurements utilizing silicon and gallium-arsenide mixer diodes

    NASA Technical Reports Server (NTRS)

    Dombrowski, M.

    1977-01-01

    An analysis was made on two commercially available silicon and gallium arsenide Schottky barrier diodes. These diodes were selected because of their particularly low noise figure in the frequency range of interest. The specified noise figure for the silicon and gallium arsenide diodes were 6.3 db and 5.3 db respectively when functioning as mixers in the 13.6 GHz region with optimum local oscillator drive.

  2. Effects of Organic Chelation on the Behavior of Aluminum Relative to Gallium During Pedogenesis

    NASA Astrophysics Data System (ADS)

    Herz, M. M.; Derry, L. A.

    2003-12-01

    This study of gallium and aluminum behavior in the soil weathering environment provides a first step toward using Ga/Al as a tracer of aluminum dynamics during pedogenesis. Previously, the interpretation of aluminum behavior in soils was confounded by the monoisotopic nature of aluminum and its subsequent lack of a comparative tracer. Like aluminum, gallium is a strongly hydrolyzing group III element. It is included in the same mineral systems as aluminum and the two are believed to have similar chemistries in most natural environments. Aluminum is a highly toxic metal whose removal from mineral matrices is enhanced by acid deposition and chelation by organic ligands. As much as 80% of dissolved aluminum in upper soil horizons can be complexed by organic ligands, most of which are secreted by plant and soil microorganisms to detoxify their surroundings. However, gallium makes comparatively unstable complexes with organic chelators, and is not expected to be carried into solution or leached from the soil profile by them to the same extent as aluminum. The Hawaiian Islands provide a unique opportunity to study the evolution of aluminum and gallium concentrations during soil development along gradients where age or climate varies, but all other soil forming factors are held constant. Ga/Al in older and more intensely weathered soils can be as high as 2.58 (mg/g), whereas the basaltic parent material is almost 10 times lower (0.30 mg/g). The factor driving soil Ga/Al ratios away from those found in parent material may be the strong control that organic chelation exerts over aluminum mobility. The enhancement of aluminum dissolution by organic chelation can be inferred from the decrease in Ga/Al ratios of exchangeable cations along a gradient of increasing rainfall; where wetter, more organic rich sites have Ga/Al ratios 10 to 100 times lower than drier sites where organic chelation is a less important factor in driving aluminum dynamics. Along this same gradient, the bulk soil shows an increase in Ga/Al despite an overall loss of both metals, indicating a relative enrichment of gallium in the secondary minerals. The results of preliminary laboratory syntheses of allophane minerals show that there is no significant fractionation of aluminum and gallium during secondary mineral formation in the absence of organic chelators.

  3. Separation and Enrichment of Gallium(III) as 4-(2-Thiazolylazo) Resorcinol (TAR) Complex by Solid Phase Extraction on Amberlite XAD-4 Adsorption Resin

    Microsoft Academic Search

    Umit Divrikli; Mustafa Soylak; Latif Elci

    2003-01-01

    A rapid, sensitive, and facile method for enrichment and separation of trace amounts of gallium was established by using mini column filled Amberlite XAD-4. Gallium(III) as a 4-(2-thiazolylazo) resorcinol (TAR) complex is sorbed on the Amberlite XAD-4 resin and is easily eluted by using 1 M nitric acid in acetone. The determinations of gallium were performed by atomic absorption spectrometry. The

  4. SUR LES DIAGRAMMES D'ALLIAGES DU GALLIUM I OU II AVEC L'TAIN, LE ZINC OU L'INDIUM

    E-print Network

    Boyer, Edmond

    17. SUR LES DIAGRAMMES D'ALLIAGES DU GALLIUM I OU II AVEC L'ÉTAIN, LE ZINC OU L'INDIUM Par Mlle S'alliages binaires du gallium I ou du gallium II avec l'étain, le zinc ou l'indium. La forme stable GaI donne des présentent la même allure ; par contre le zinc ou l'indium donnent des composés intermétallique savec le

  5. Ductile ordered intermetallic alloys.

    PubMed

    Liu, C T; Stiegler, J O

    1984-11-01

    Many ordered intermetallic alloys have attractive high-temperature properties; however, low ductility and brittle fracture limit their use for structural applications. The embrittlement in these alloys is mainly caused by an insufficient number of slip systems (bulk brittleness) and poor grain-boundary cohesion. Recent studies have shown that the ductility and fabricability of ordered intermetallics can be substantially improved by alloying processes and control of microstructural features through rapid solidification and thermomechanical treatments. These results demonstrate that the brittleness problem associated with ordered intermetallics can be overcome by using physical metallurgical principles. Application of these principles will be illustrated by results on Ni(3)Al and Ni(3)V-Co(3)V-Fe(3)V. The potential for developing these alloys as a new class of high-temperature structural materials is discussed. PMID:17774926

  6. Electroplating on titanium alloy

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1971-01-01

    Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

  7. Osteomyelitis and infarction in sickle cell hemoglobinopathies: differentiation by combined technetium and gallium scintigraphy

    SciTech Connect

    Amundsen, T.R.; Siegel, M.J.; Siegel, B.A.

    1984-12-01

    Clinical records and scintigrams were reviewed of 18 patients with sickle cell hemoglobinophaties who had undergone combined technetium and gallium scintigraphy during 22 separate episodes of suspected osseous infection. The combined scintigrams were correctly interpreted as indicating osteomyelitis in four studies. Of 18 studies in patients with infarction, the combined scintigrams were correctly interpreted in 16 and showed either no local accumulation of Ga-67 or less accumulation than that of Tc-99m MDP at symptomatic sites. In the other two studies, the scintigrams were falsely interpreted as indicating osteomyelitis and showed congruent, increased accumulation of both Tc-99, MDP and Ga-67. This pattern must be considered indeterminate. Overall, the results indicate that the combination of technetium and gallium scintigraphy is an effective means to distinguish osteomyelitis from infarction in patients with sickle cell hemoglobinopathies.

  8. Fast neutron scattering on Gallium target at 14.8 MeV

    E-print Network

    R. Han; R. Wada; Z. Chen; Y. Nie; X. Liu; S. Zhang; P. Ren; B. Jia; G. Tian; F. Luo; W. Lin; J. Liu; F. Shi; M. Huang; X. Ruan; J. Ren; Z. Zhou; H. Huang; J. Bao; K. Zhang; B. Hu

    2014-11-03

    Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

  9. Fast neutron scattering on Gallium target at 14.8 MeV

    E-print Network

    Han, R; Chen, Z; Nie, Y; Liu, X; Zhang, S; Ren, P; Jia, B; Tian, G; Luo, F; Lin, W; Liu, J; Shi, F; Huang, M; Ruan, X; Ren, J; Zhou, Z; Huang, H; Bao, J; Zhang, K; Hu, B

    2014-01-01

    Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

  10. Preliminary results from the Russian-American gallium experiment Cr-neutrino source measurement

    SciTech Connect

    Elliott, S.R. [Washington Univ., Seattle, WA (United States); Abdurashitov, J.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research; Bowles, T.J. [Los Alamos National Lab., NM (United States)] [and others

    1995-12-31

    The Russian-American Gallium Experiment has been collecting solar neutrino data since early 1990. The flux measurement of solar neutrinos is well below that expected from solar models. We discuss the initial results of a measurement of experimental efficiencies by exposing the gallium target to neutrinos from an artificial source. The capture rate of neutrinos from this source is very close to that which is expected. The result can be expressed as a ratio of the measured capture rate to the anticipated rate from the source activity. This ratio is 0.93 + 0.15, {minus}0.17 where the systematic and statistical errors have been combined. To first order the experimental efficiencies are in agreement with those determined during solar neutrino measurements and in previous auxiliary measurements. One must conclude that the discrepancy between the measured solar neutrino flux and that predicted by the solar models can not arise from an experimental artifact. 17 refs., 3 figs., 1 tab.

  11. Origin of color centers in the flux-grown europium gallium garnet

    SciTech Connect

    Aleksandrovsky, A. S.; Arkhipkin, V. G.; Bezmaternykh, L. N.; Gudim, I. A.; Krylov, A. S. [L. V. Kirensky Institute of Physics, Akademgorodok, Krasnoyarsk 660036, Russia and Siberian Federal University, Krasnoyarsk 660079 (Russian Federation); Vagizov, F. [Department of Physics, Texas A and M University, College Station, Texas 77840 (United States)

    2008-04-15

    Europium gallium garnet (EuGG) single crystals were grown from fluxes with various contents. Optical absorption spectra of EuGG grown from a flux containing calcium show an additional band in the ultraviolet and blue regions of the spectra as compared to the case of a calcium-free flux. Moessbauer spectra of the samples grown from the fluxes with different additives show no signs of other valence states of the europium ions except for 3+. However, they indicate changes in the crystal field due to the entrance of additive ions. The nature of the additional absorption must be the same as that for calcium-doped gadolinium gallium garnet, i.e., anion vacancies. Moessbauer isotope shifts and quadrupole splitting for EuGG are determined.

  12. The Baksan Neutrino Observatory Soviet-American Gallium Solar Neutrino Experiment

    SciTech Connect

    Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.V.; Avdeyev, A.V.; Belouska, Yu. I.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gavrin, V.N.

    1988-01-01

    A radiochemical /sup 71/Ga-/sup 71/Ge experiment to determine the integral flux of neutrinos from the sun is currently under preparation at the Baksan Neutrino Observatory in the USSR. Measurements are scheduled to commence by late 1988 with 30 tonnes of metallic gallium. A fractional statistical accuracy of 18% is expected to be obtained after one year of operation if the solar signal obtained after one year of operation if the solar signal is 70 SNU, the flux expected from p-p neutrinos alone. While initial measurements are in progress, 30 additional tonnes of gallium will be installed in order to perform the full experiment with a 60-tonne target. 28 refs.

  13. Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet

    SciTech Connect

    Murphy, R.W.

    1994-12-01

    Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

  14. Synthesis, Structure, and Antiproliferative Activity of Three Gallium(III) Azole Complexes

    PubMed Central

    Zanias, Stergios; Papaefstathiou, Giannis S.; Raptopoulou, Catherine P.; Papazisis, Konstantinos T.; Vala, Vasiliki; Zambouli, Dimitra; Kortsaris, Alexandros H.; Kyriakidis, Dimitrios A.; Zafiropoulos, Theodoros F.

    2010-01-01

    As part of our interest into the bioinorganic chemistry of gallium, gallium(III) complexes of the azole ligands 2,1,3-benzothiadiazole (btd), 1,2,3-benzotriazole (btaH), and 1-methyl-4,5-diphenylimidazole (L) have been isolated. Reaction of btaH or btd with GaBr3 or GaCl3 resulted in the mononuclear complexes [GaBr3(btaH)2] (1) and [GaCl3(btd)2] (2), respectively, while treatment of GaCl3 with L resulted in the anionic complex (LH)2[GaCl4] (3). All three complexes were characterized by single-crystal X-ray crystallography and IR spectroscopy, while their antiproliferative activities were investigated against a series of human and mouse cancer cell lines. PMID:20721278

  15. Surface orientation as a control parameter for the growth of non-stoichiometric gallium arsenide

    NASA Astrophysics Data System (ADS)

    Marek, T.; Schür, C.; Kunsági-Máté, S.

    2005-12-01

    In order to study the effect of the substrate orientation on the incorporation of excess arsenic into low temperature grown gallium arsenide, we examine molecular beam epitaxial layers grown at constant low substrate temperatures and constant III/V flux ratio on exactly (001) oriented substrates and on vicinal substrates tilted up to 10° towards the 111A and 111B directions. Our experiments show that the substrate orientation has a significant influence on the excess arsenic content and thus needs to be considered as an additional parameter to control low temperature growth of gallium arsenide. Respective ab-initio calculations offer first models for the incorporation of excess arsenic into As antisite and As interstitial positions on misoriented as well as exactly oriented substrates.

  16. Investigation of spin transport and accumulation in aluminum gallium arsenide

    NASA Astrophysics Data System (ADS)

    Misuraca, Jennifer

    This dissertation describes spin injection, transport, and detection experiments from Fe electrodes into a bulk AlGaAs channel. This semiconducting alloy is one of a class of persistent photoconductors, chosen as the spin transport medium because its carrier density can be tuned in a controlled manner via photoexcitation through the metal to insulator transition (MIT) in situ. This allows one to determine the dependence of spin lifetime on a variety of external parameters including carrier density, all on one sample. This research represents the first electrical spin-dependent measurements in this material and describes the dependence of the Hanle signal size and spin lifetime on bias, temperature, and carrier density. The photoexcitation needed to change the carrier density in this material comes from an infrared light-emitting diode (IR LED). The first step of this project was to characterize the new, highly Si doped Al0.3Ga 0.7As heterostructures, in order to determine how the illumination of the sample will affect the parameters of the material. To complete this study, Hall crosses were fabricated from the AlGaAs material and the transport properties were measured between 350 mK and 165 K. The resistivity, carrier density, and mobility were determined as a function of temperature for a variety of different illumination times. From this data, the MIT, scattering mechanisms, and the shape of the band tail of the density of states (DOS) were investigated. In fact, this is the first work to electrically probe the DOS in AlGaAs. Once the materials were characterized, they were used to fabricate lateral spin transport devices. Spin transport and accumulation were studied in detail via Hanle effect measurements, which measure the dephasing of electron spins in a perpendicular magnetic field. From these measurements, the spin lifetime of the material can be calculated, and is in the nanosecond range for all measured carrier densities. The spin lifetimes are measured using three distinct measurement configurations which all give consistent results. The dependence of spin lifetime and Hanle signal size are reported as a function of bias, temperature, and carrier density. This is the first spin transport experiment using a persistently photoconductive material as the spin transport channel in order to change the carrier density of the material in situ. The research in this dissertation successfully provides a framework for the continuation of spin injection and detection studies in this and other alloy semiconductors, and provides insight into how the spin lifetime depends on the doping levels in semiconductors.

  17. Epitaxial metal-gallium arsenide contacts via electrodeposition

    NASA Astrophysics Data System (ADS)

    Bao, Zhi Liang

    The fabrication of epitaxial metal-GaAs contacts via electrodeposition and the electrical properties of the Schottky diodes are reported in this dissertation. Epitaxial electrodeposition of copper, iron, cobalt, iron-nickel, and bismuth on GaAs was discovered to rely on three major factors: the preparation of the GaAs surface by (NH4)OH etching, the addition of (NH 4)2SO4 to the electrolytes, and the control of deposition current density. The surface preparation by (NH4)OH provides a hydrophilic surface likely due to passivation via a layer of hydroxide bonds. Ammonium sulphate inhibits oxidation of the metal cations and likely acts as a surfactant both on the metal and GaAs surfaces. Control of adatom flux, similar to vacuum deposition techniques such as molecular beam epitaxy, determined the crystallinity, varying from polycrystalline to epitaxial to dendritic for current densities from 0.01 to 1 mA/mm2. The effects of other electrodeposition conditions including pH and electrolyte temperature were also investigated. Neutral electrolytes are needed for copper, iron, nickel-iron alloy, and cobalt epitaxial deposition, while acidic solution works for bismuth deposition indicating that the control of hydrogen evolution may be important. Cobalt nanodisc formation was obtained for lower temperatures (2 - 22°C) while optimal copper, iron, and bismuth epitaxy required higher deposition temperatures, 53, 56, and 70°C, respectively. The growth is via island nucleation and coalescence. The iron films develop a small decrease in lattice constant with residual compressive stress, which is a function of temperature. This is likely due to an impurity such as oxygen. Copper and cobalt formed nanometer scale reacted interfaces with GaAs, while iron and bismuth/GaAs formed abrupt interfaces. The electrical properties of these Schottky diodes were, nevertheless, found to be close to ideal and comparable to vacuum deposited diodes. Fe and Co/GaAs diodes showed identical electrical properties for GaAs (100), (110) and (111)B substrate orientations, consistent with uniform and defect-free interfaces. Cu and Bi/GaAs showed a much greater orientational dependence perhaps due to the larger lattice mismatch. Iron and nickel-iron alloy films showed anisotropic magnetic properties consistent with single crystalline material. These metal/GaAs contacts are potentially interesting for spintronics applications. Keywords. electrodeposition; epitaxy; metal-GaAs; Spintronics; (NH4)2SO4

  18. Mechanical alloying and milling

    Microsoft Academic Search

    C. Suryanarayana

    2001-01-01

    Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from

  19. Rayleigh–Benard oscillatory natural convection of liquid gallium heated from below

    Microsoft Academic Search

    Yoji Yamanaka; Koichi Kakimoto; Hiroyuki Ozoe; Stuart W. Churchill

    1998-01-01

    The average rate of heat transfer as well as the oscillatory span-widths of the Nusselt number and the Rayleigh number were measured for natural convection in a layer of liquid gallium (Pr=0.023) heated from below electrically and cooled from above with running water. These quantities were determined by measuring the instantaneous temperature difference between the upper and lower horizontal copper

  20. The Effects of Thermal Cycling on Gallium Nitride and Silicon Carbide Semiconductor Devices for Aerospace Use

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These Include radiation, extreme temperatures, thermal cycling, to name a few. Preliminary data obtained on new Gallium Nitride and Silicon Carbide power devices under exposure to radiation followed by long term thermal cycling are presented. This work was done in collaboration with GSFC and JPL in support of the NASA Electronic Parts and Packaging (NEPP) Program

  1. Light-induced phase and amplitude gratings in centrosymmetric Gadolinium Gallium garnet doped with calcium.

    PubMed

    Ellabban, Mostafa A; Fally, Martin; Rupp, Romano A; Kovács, László

    2006-01-23

    The photosensitive properties of a centrosymmetric gadolinium gallium garnet crystal doped with calcium are investigated at room temperature. Elementary holograms can be recorded over a wide range of wavelengths in the visible spectral range. The photosensitive properties are studied experimentally using beam coupling and angular response experiments. Mixed absorption and refractive-index gratings are observed and their amplitudes and relative phases determined. Moreover, the candidate centers that are responsible for the photorefractive effect are discussed. PMID:19503376

  2. Optical absorption of Ni2+ and Ni3+ ions in gadolinium gallium garnet epitaxial films

    NASA Astrophysics Data System (ADS)

    Vasileva, N. V.; Gerus, P. A.; Sokolov, V. O.; Plotnichenko, V. G.

    2012-12-01

    Single-crystal Ni-doped gadolinium gallium garnet films were grown for the first time from supercooled Bi2O3-B2O3-based melt solutions by liquid-phase epitaxy. Optical absorption bands due to Ni2+, Ni3+ and Bi3+ ions were observed in those films. Interpretation and tabulation of all absorption bands of nickel ions occupying octahedral and tetrahedral sites in the garnet lattice are presented.

  3. The suitability of gallium as a substitute for aluminum in tracing experiments

    Microsoft Academic Search

    Rachel C. Walton; Keith N. White; Francis Livens; Catherine R. McCrohan

    2010-01-01

    Aluminum is a toxic metal whose complex aquatic chemistry, mechanisms of toxicity and trophic transfer are not fully understood.\\u000a The only isotope of Al suitable for tracing experiments in organisms—26Al—is a rare, costly radioisotope with a low emission energy, making its use difficult. Gallium shares a similar chemistry\\u000a with Al and was therefore investigated as a potential substitute for Al

  4. Evaluation of Gallium68 Tris(2-Mercaptobenzyl)Amine: A Complex with Brain and Myocardial Uptake

    Microsoft Academic Search

    Cathy S. Cutler; M. Cecilia Giron; David E. Reichert; Abraham Z. Snyder; Pilar Herrero; Carolyn J. Anderson; Duncan A. Quarless; Stephen A. Koch; Michael J. Welch

    1999-01-01

    Previous research into development of a gallium-radiolabeled agent that crosses the blood- brain barrier has met with limited success. In this study, we focused our attention on a Ga(III) complex of a 4-coordinate amine trithiolate tripod ligand, tris(2-mercaptobenzyl) amine (S3N). The Ga(III) S3N complex is small, neutral, and lipophilic, meeting the requirements for a potential brain imaging agent. The Ga-68

  5. Evaluation of gallium-68 tris(2-mercaptobenzyl)amine: a complex with brain and myocardial uptake

    Microsoft Academic Search

    Cathy S Cutler; M. Cecilia Giron; David E Reichert; Abraham Z Snyder; Pilar Herrero; Carolyn J Anderson; Duncan A Quarless; Stephen A Koch; Michael J Welch

    1999-01-01

    Previous research into development of a gallium-radiolabeled agent that crosses the blood–brain barrier has met with limited success. In this study, we focused our attention on a Ga(III) complex of a 4-coordinate amine trithiolate tripod ligand, tris(2-mercaptobenzyl) amine (S3N). The Ga(III) S3N complex is small, neutral, and lipophilic, meeting the requirements for a potential brain imaging agent. The Ga-68 complex

  6. The optical and electrical effects of high concentrations of defects in irradiated crystalline gallium arsenide

    Microsoft Academic Search

    R. Coates; E. W. J. Mitchell

    1975-01-01

    The damage produced by fast neutron irradiation of gallium arsenide has been studied by a number of techniques. The electrical resistivity, which increases with dose at low doses to semi-insulating values, shows a remarkable, specimen-independent decrease for doses greater than 1017 n cm-2 from values of ca. 109 Omega cm to 3 Omega cm for the highest dose of 1.5

  7. Optical and electric properties of aluminum-gallium doped zinc oxide for transparent conducting film

    Microsoft Academic Search

    Meng-Chi Li; Chien-Cheng Kuo; Sheng-Hui Chen; Cheng-Chung Lee

    2009-01-01

    The well-known indium-tin-oxide is not suitable for solar cell, because of the chemical reduction, even without any hydrogen dilution. The inexpensive and non-toxic of transparent conducting Aluminum and Gallium doped ZnO (AZO and GZO) thin films have been investigated for the substitutes for the indium-tin-oxide thin films. AZO performs high transmittance at visible region, however, higher resistance than GZO. In

  8. The Ammonothermal Crystal Growth of Gallium Nitride—A Technique on the Up Rise

    Microsoft Academic Search

    Dirk Ehrentraut; Tsuguo Fukuda

    2010-01-01

    Gallium nitride (GaN) is one of the most important wide band gap semiconductor materials in modern technology with even higher expectations for future applications it is ought to play a crucial role. Among this, the growth of lattice and thermally matched GaN substrates for the GaN device technology takes an essential piece. This paper is reporting on the achievements in

  9. Minimum loss predictions and measurements in gallium lanthanum sulphide based glasses and fibre

    Microsoft Academic Search

    D. J. Brady; T. Schweizer; J. Wang; D. W. Hewak

    1998-01-01

    Measurements of the fundamental optical absorptions of gallium and lanthanum sulphide based chalcogenide glasses (Ga:La:S, and Ga:La:S:O) in glass and glass fibre forms are presented. Theoretical predictions of the minimum material losses in these glasses are given by calculating the loss from Rayleigh scattering and fitted data from the fundamental glass absorptions. The theoretical minimum loss for Ga:La:S is 0.5

  10. EXAFS study on liquid gallium under high pressure and high temperature.

    PubMed

    Comez, L; Di Cicco, A; Minicucci, M; Tossici, R; Itié, J P; Polian, A

    2001-03-01

    EXAFS (Extended X-ray Absorption Fine Structure) spectra of liquid gallium near the Ga K-edge have been collected in wide pressure and temperature ranges. Reliable short-range pair distribution functions have been determined using advanced ab-initio calculations (GNXAS) taking into account the medium and long-range structure obtained by previous neutron and x-ray-scattering studies. PMID:11512928

  11. Systems engineering and technical assistance in support of digital gallium arsenide insertion projects

    Microsoft Academic Search

    Daniel H. Butler

    1992-01-01

    Booz-Allen provided a high level of support, including systems engineering analyses and technical assistance for systems insertion efforts using digital Gallium Arsenide (GaAs). Once insertion candidates were chosen, Booz-Allen supported the insertion efforts by acting as a liaison between the government and GaAs contractors, attending and arranging contractor reviews, providing meeting facilities, and producing presentation materials. A major accomplishment under

  12. Gallium arsenide (GaAs) nanofibers by electrospinning technique as future energy server materials

    Microsoft Academic Search

    Faheem A. Sheikh; Nasser A. M. Barakat; Muzafar A. Kanjwal; S. J. Park; Hern Kim; Hak Yong Kim

    2010-01-01

    Gallium arsenide (GaAs) does have superior electronic properties compared with silicon. For instant, it has a higher saturated\\u000a electron velocity and higher electron mobility. Weak mechanical properties and high production cost are the main drawbacks\\u000a of this interesting semiconductor. In this study, we are introducing production of GaAs nanofibers by electrospinning methodology\\u000a as a very low cost and yielding distinct

  13. Contribution of gallium experiments to the understanding of solar physics and neutrino physics

    SciTech Connect

    Gavrin, V. N., E-mail: gavrin@inr.ru [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

    2013-10-15

    The results of gallium measurements of solar neutrino and measurements with artificial sources of neutrinos are presented. Conclusions are drawn from these results, and the potential of the SAGE experiment for studying transitions of active neutrinos to sterile states for {Delta}m{sup 2} > 0.5 eV{sup 2} and a sensitivity of a few percent to the disappearance of electron neutrinos is examined.

  14. Removal and recovery of gallium ion from solution by insoluble amphoteric starches

    Microsoft Academic Search

    Wu-Chung Chan; Wuchung

    1993-01-01

    The removal and recovery of gallium ion (Ga[sup +3]) from a solution with the high cross-linked amphoteric starches containing the phosphate anionic group and the quaternary ammonium or tertiary amine cationic group was investigated. The adsorption capacity of tertiary amine phosphate starch (TAP) and quaternary ammonium phosphate starch (QAP) is 0.54 and 0.48 meq\\/g, respectively. The adsorption process has been

  15. Highly stable transparent and conducting gallium-doped zinc oxide thin films for photovoltaic applications

    Microsoft Academic Search

    E. Fortunato; L. Raniero; L. Silva; A. Gonçalves; A. Pimentel; P. Barquinha; H. Águas; L. Pereira; G. Gonçalves; I. Ferreira; E. Elangovan; R. Martins

    2008-01-01

    Transparent and highly conducting gallium zinc oxide (GZO) films were successfully deposited by RF sputtering at room temperature. A lowest resistivity of ?2.8×10?4?cm was achieved for a film thickness of 1100nm (sheet resistance ?2.5?\\/?), with a Hall mobility of 18cm2\\/Vs and a carrier concentration of 1.3×1021cm?3. The films are polycrystalline with a hexagonal structure having a strong crystallographic c-axis orientation.

  16. Very High Speed Integrated Circuits\\/Gallium Arsenide Electronics for Aircraft Engine Controls

    Microsoft Academic Search

    Mark A. Overstreet

    1988-01-01

    VHSIC (Very High Speed Integrated Circuits) and GaAs (Gallium Arsenide) technologies offer increased performance and GaAs, in particular, offers unique capabilities in adverse environments, such as high temperature and radiation. VHSIC, as defined by code Federal regulation, is any device that has military applications, and equals or exceeds 1 ?? 1013 Gate Hz\\/cm2. VHSIC technology offers potential speed and performance

  17. Antitumor Activity and Toxicity of Salts of Inorganic Group IIIa Metals: Aluminum, Gallium, Indium, and Thallium

    Microsoft Academic Search

    Michael M. Hart; Richard H. Adamson

    1971-01-01

    The toxicity and antitumor activity of salts of the Group IIIa metals aluminum, gallium, indium, and thallium were determined. With the (lethal dose)50 as a measure, the decreasing order of toxicity was TlCl3>= In(NO3)3> Ga(NO3)3 > Al(NO3)3. All four metals exhibited antitumor activity, but when the tumor was inoculated by a route different from that of the drug, only Ga+3

  18. Surface Layering in Liquid Gallium: An X-Ray Reflectivity Study

    Microsoft Academic Search

    M. J. Regan; E. H. Kawamoto; S. Lee; P. S. Pershan; N. Maskil; M. Deutsch; O. M. Magnussen; B. M. Ocko; L. E. Berman

    1995-01-01

    Surface-induced atomic layering in liquid gallium has been observed using x-ray reflectivity, ultrahigh vacuum conditions, and sputtered clean surfaces. Reflectivity data, collected on a supercooled liquid sample to momentum transfers as large as qz = 3.0 Å-1, exhibit a strong maximum near 2.4 Å -1 indicating a layer spacing that is comparable to its atomic dimensions. The amplitude of the

  19. Surface layering in liquid gallium: An X-ray reflectivity study

    Microsoft Academic Search

    M. J. Regan; E. H. Kawamoto; S. Lee; P. S. Pershan; N. Maskil; M. Deutsch; O. M. Magnussen; B. M. Ocko; L. E. Berman

    1995-01-01

    Surface-induced atomic layering in liquid gallium has been observed using x-ray reflectivity, ultrahigh vacuum conditions, and sputtered clean surfaces. Reflectivity data, collected on a supercooled liquid sample to momentum transfers as large as {ital q}{sub {ital z}}=3.0 A⁻¹, exhibit a strong maximum near 2.4 A⁻¹ indicating a layer spacing that is comparable to its atomic dimensions. The amplitude of the

  20. An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1988-01-01

    The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).

  1. Surface Passivation for 3-5 Semiconductor Processing: Stable Gallium Sulphide Films by MOCVD

    NASA Technical Reports Server (NTRS)

    Macinnes, Andrew N.; Jenkins, Phillip P.; Power, Michael B.; Kang, Soon; Barron, Andrew R.; Hepp, Aloysius F.; Tabib-Azar, Massood

    1994-01-01

    Gallium sulphide (GaS) has been deposited on GaAs to form stable, insulating, passivating layers. Spectrally resolved photoluminescence and surface recombination velocity measurements indicate that the GaS itself can contribute a significant fraction of the photoluminescence in GaS/GaAs structures. Determination of surface recombination velocity by photoluminescence is therefore difficult. By using C-V analysis of metal-insulator-semiconductor structures, passivation of the GaAs with GaS films is quantified.

  2. Ultrahigh temperature intermetallic alloys

    SciTech Connect

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.

    1998-11-01

    A new family of Cr-Cr{sub 2}Ta intermetallic alloys based on Cr-(6--10)Ta (at.%) is under development for structural use in oxidizing environments in the 1,000-1,300 C (1,832--2,372 F) temperature range. Development objectives relate to high temperature strength and oxidation resistance and room temperature fracture toughness. The 1,200 C (2,192 F) strength goals have been met: yield and fracture strengths of 275 MPa (40 ksi) and 345 MPa (50 ksi), respectively, were achieved. Progress in attaining reasonable fracture toughness of Cr-Cr{sub 2}Ta alloys has been made; current alloys exhibit room-temperature values of about 10--12 MPa{radical}m (1.1 MPa{radical}m = 1 ksi{radical}in.). Oxidation rates of these alloys at 950 C (1,742 F) in air are in the range of those reported for chromia-forming alloys. At 1,100 C (2,012 F) in air, chromia volatility was significant but, nevertheless, no scale spallation and positive weight gains of 1--5 mg/cm{sup 2} have been observed during 120-h, 6-cycle oxidation screening tests. These mechanical and oxidative properties represent substantial improvement over Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr alloys previously developed.

  3. Water-soluble cationic gallium(III) and indium(III) phthalocyanines for photodynamic therapy.

    PubMed

    Durmu?, Mahmut; Ahsen, Vefa

    2010-03-01

    The new tetra-non-peripheral and peripheral 2-mercaptopyridine substituted gallium(III) and indium(III) phthalocyanine complexes (np-GaPc, p-GaPc, np-InPc and p-InPc) and their quaternized derivatives (Qnp-GaPc, Qp-GaPc, Qnp-InPc and Qp-InPc) have been synthesized and characterized. The quaternized complexes show excellent solubility in water, which makes them potential photosensitizer for use in photodynamic therapy (PDT) of cancer. Photophysical and photochemical properties of these phthalocyanines were investigated. General trends are described for quantum yields of photodegradation, fluorescence and fluorescence lifetimes as well as singlet oxygen quantum yields of these compounds. In this study, the effects of the position of the substituents, the nature of the metal ion and quaternization of the substituents on the photophysical and photochemical parameters of the gallium(III) and indium(III) phthalocyanines are also reported. This study also presented the ionic gallium(III) and indium(III) phthalocyanines strongly bind to bovine serum albumin (BSA). PMID:20083308

  4. Detection of insulinoma using 68Gallium-DOTATATE PET/CT: a case report

    PubMed Central

    Neychev, Vladimir; Cottle-Delisle, Candice; Merkel, Roxanne; Yang, Lily A.; Quezado, Martha M.; Chang, Richard; Kebebew, Electron

    2014-01-01

    Insulinomas are the most common cause of endogenous hyperinsulinemic hypoglycemia in non-diabetic adults. They are most often benign, small and difficult to localize with current imaging techniques. This is of high importance, as complete surgical resection is the only curative treatment. Anatomic imaging, 111In-pentetreotide scan and 68Gallium-DOTATATE positron emission tomography/computed tomography (PET/CT) were compared in a patient with insulinoma. 68Gallium-DOTATATE PET/CT and selective arterial calcium stimulation localized the insulinoma. At surgery, a tumor in the anterior aspect of the pancreatic body was found which confirmed the preoperative localization, and a 2.1 cm tumor was enucleated, World Health Organization (WHO) grade I insulinoma. The patient remains euglycemic and free of symptoms at last follow up. In conclusion, 68Gallium-DOTATATE PET/CT imaging may be a useful adjunct localizing study for insulinomas. It is a non-invasive preoperative localization study that could guide surgical exploration for successful therapy. PMID:25493261

  5. New Techniques of Laser Spectroscopy on Exotic Isotopes of Gallium and Francium

    E-print Network

    Procter, Thomas John

    The neutron-deficient gallium isotopes down to N=32 have had their hyperfine structures and isotope shifts measured via collinear laser spectroscopy using the COLLAPS (COllinear LAser sPectroScopy) beam line. The ground-state spin of 63Ga has been determined as I = 3/2 and its magnetic dipole and electric quadrupole moments were measured to be µ = +1.469(5) µN and Qs = +0.212(14) b respectively. The nuclear moments of 70Ga were measured to be µ = +0.571(2) µN and Qs = +0.105(7) b. New isotope shift results were combined with previously measured values of the neutron-rich isotopes and the changes in mean-square charge radii of the entire gallium isotope chain were investigated. Analysis of the trend in the neutron-deficient charge radii demonstrated that there is no evidence of anomalous charge radii behaviour in gallium in the region of N=32. A sudden increase of the charge radii was observed at the N=50 shell gap and an inversion of the normal odd-even staggering effect was seen at N=40.The development o...

  6. Proton and gallium(III) binding properties of a biologically active salicylidene acylhydrazide.

    PubMed

    Hakobyan, Shoghik; Boily, Jean-François; Ramstedt, Madeleine

    2014-09-01

    Bacterial biofilm formation causes a range of problems in our society, especially in health care. Salicylidene acylhydrazides (hydrazones) are promising antivirulence drugs targeting secretion systems used during bacterial infection of host cells. When mixed with the gallium ion they become especially potent as bacterial and biofilm growth-suppressing agents, although the mechanisms through which this occurs are not fully understood. At the base of this uncertainty lies the nature of hydrazone-metal interactions. This study addresses this issue by resolving the equilibrium speciation of hydrazone-gallium aqueous solutions. The protonation constants of the target 2-oxo-2-[N-(2,4,6-trihydroxy-benzylidene)-hydrazino]-acetamide (ME0163) hydrazone species and of its 2,4,6-trihydroxybenzaldehyde and oxamic acid hydrazide building blocks were determined by UV-visible spectrophotometry to achieve this goal. These studies show that the hydrazone is an excessively strong complexing agent for gallium and that its antivirulence properties are predominantly ascribed to monomeric 1:1Ga-ME0163 complexes of various Ga hydrolysis and ME0163 protonation states. The chelation of Ga(III) to the hydrazone also increased the stability of the compounds against acid-induced hydrolysis, making this group of compounds very interesting for biological applications where the Fe-antagonist action of both Ga(III) and the hydrazone can be combined for enhanced biological effect. PMID:24837332

  7. Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function

    NASA Astrophysics Data System (ADS)

    Adolfsson, Karl; Schneider, Martina; Hammarin, Greger; Häcker, Udo; Prinz, Christelle N.

    2013-07-01

    Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III-V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.

  8. Preparation of gallium nitride surfaces for atomic layer deposition of aluminum oxide

    SciTech Connect

    Kerr, A. J. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States); Chagarov, E.; Kaufman-Osborn, T.; Kummel, A. C., E-mail: akummel@ucsd.edu [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States); Gu, S.; Wu, J.; Asbeck, P. M. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); Madisetti, S.; Oktyabrsky, S. [Department of Nanoscale Science and Engineering, University at Albany–State University of New York, Albany, New York 12222 (United States)

    2014-09-14

    A combined wet and dry cleaning process for GaN(0001) has been investigated with XPS and DFT-MD modeling to determine the molecular-level mechanisms for cleaning and the subsequent nucleation of gate oxide atomic layer deposition (ALD). In situ XPS studies show that for the wet sulfur treatment on GaN(0001), sulfur desorbs at room temperature in vacuum prior to gate oxide deposition. Angle resolved depth profiling XPS post-ALD deposition shows that the a-Al{sub 2}O{sub 3} gate oxide bonds directly to the GaN substrate leaving both the gallium surface atoms and the oxide interfacial atoms with XPS chemical shifts consistent with bulk-like charge. These results are in agreement with DFT calculations that predict the oxide/GaN(0001) interface will have bulk-like charges and a low density of band gap states. This passivation is consistent with the oxide restoring the surface gallium atoms to tetrahedral bonding by eliminating the gallium empty dangling bonds on bulk terminated GaN(0001)

  9. Gallium hole traps in irradiated KTiOPO4:Ga crystals

    NASA Astrophysics Data System (ADS)

    Grachev, V.; Meyer, M.; Hunt, A. W.; Malovichko, G.

    2014-12-01

    Nominally pure and gallium doped single crystals of potassium titanyl phosphate (KTiOPO4) have been studied by Electron Paramagnetic Resonance at low temperatures before and after irradiation. Irradiation with 20 MeV electrons performed at room temperature and liquid nitrogen temperature caused an appearance of electrons and holes. Gallium impurities act as hole traps in KTiOPO4 creating Ga4+ centers. Two different Ga4+ centers were observed, Ga1 and Ga2. The Ga1 centers are dominant in Ga-doped samples. For the Ga1 center, a superhyperfine structure with one nucleus with nuclear spin ½ was registered and attributed to the interaction of gallium electrons with a phosphorus nucleus or proton in its surrounding. In both Ga1 and Ga2 centers, Ga4+ ions substitute for Ti4+ ions, but with a preference to one of two electrically distinct crystallographic positions (site selective substitution). The Ga doping eliminates one of the shortcomings of KTP crystals—ionic conductivity of bulk crystals. However, this does not improve significantly the resistance of the crystals to electron and ?-radiation.

  10. Performance of a Medipix3RX Spectroscopic Pixel Detector With a High Resistivity Gallium Arsenide Sensor.

    PubMed

    Hamann, Elias; Koenig, Thomas; Zuber, Marcus; Cecilia, Angelica; Tyazhev, Anton; Tolbanov, Oleg; Procz, Simon; Fauler, Alex; Baumbach, Tilo; Fiederle, Michael

    2015-03-01

    High resistivity gallium arsenide is considered a suitable sensor material for spectroscopic X-ray imaging detectors. These sensors typically have thicknesses between a few hundred ?m and 1 mm to ensure a high photon detection efficiency. However, for small pixel sizes down to several tens of ?m, an effect called charge sharing reduces a detector's spectroscopic performance. The recently developed Medipix3RX readout chip overcomes this limitation by implementing a charge summing circuit, which allows the reconstruction of the full energy information of a photon interaction in a single pixel. In this work, we present the characterization of the first Medipix3RX detector assembly with a 500 ?m thick high resistivity, chromium compensated gallium arsenide sensor. We analyze its properties and demonstrate the functionality of the charge summing mode by means of energy response functions recorded at a synchrotron. Furthermore, the imaging properties of the detector, in terms of its modulation transfer functions and signal-to-noise ratios, are investigated. After more than one decade of attempts to establish gallium arsenide as a sensor material for photon counting detectors, our results represent a breakthrough in obtaining detector-grade material. The sensor we introduce is therefore suitable for high resolution X-ray imaging applications. PMID:24759983

  11. Detection of insulinoma using (68)Gallium-DOTATATE PET/CT: a case report.

    PubMed

    Sadowski, Samira M; Neychev, Vladimir; Cottle-Delisle, Candice; Merkel, Roxanne; Yang, Lily A; Quezado, Martha M; Chang, Richard; Kebebew, Electron

    2014-11-01

    Insulinomas are the most common cause of endogenous hyperinsulinemic hypoglycemia in non-diabetic adults. They are most often benign, small and difficult to localize with current imaging techniques. This is of high importance, as complete surgical resection is the only curative treatment. Anatomic imaging, (111)In-pentetreotide scan and (68)Gallium-DOTATATE positron emission tomography/computed tomography (PET/CT) were compared in a patient with insulinoma. (68)Gallium-DOTATATE PET/CT and selective arterial calcium stimulation localized the insulinoma. At surgery, a tumor in the anterior aspect of the pancreatic body was found which confirmed the preoperative localization, and a 2.1 cm tumor was enucleated, World Health Organization (WHO) grade I insulinoma. The patient remains euglycemic and free of symptoms at last follow up. In conclusion, (68)Gallium-DOTATATE PET/CT imaging may be a useful adjunct localizing study for insulinomas. It is a non-invasive preoperative localization study that could guide surgical exploration for successful therapy. PMID:25493261

  12. molecular dynamics study of the gallium vacancy diffusion in GaAs

    NASA Astrophysics Data System (ADS)

    Bockstedte, Michel; Scheffler, Matthias

    1996-03-01

    Experimentally(T. Y. Tan et al.), Rev. Solid State Mater. Sci. 17, 47 (1991). it is well established that cation self-diffusion in GaAs proceeds by gallium vacancies. An analysis(J-L. Rouviere et al.), Phys. Rev. Lett. 68, 2798 (1992). of diffusion experiments yielded an exceptionally high value for the formation entropy of 32.9 kB and a migration energy barrier of 1.7 eV. The physics underlying this result is quite puzzling. Even the question whether the diffusion involves only the gallium sublattice or whether it proceeds by nearest neighbor hops is unanswered. Employing ab initio molecular dynamics simulations we analyze the motion of atoms and evaluate the free energy of vacancy formation and the diffusion constant. For the Ga vacancy we obtain a value for the formation entropy of 8 kB - comparable to that of the vacancy in silicon - but significantly lower than that extracted from experimentfootnotemark[2]. Based on our studies we therefore dare to question the experimental analysis. The calculated motion of a gallium vacancy close to the melting temperature of GaAs and the analysis of the different diffusion events exclude a diffusion mechanism by nearest neighbor hops. We discuss the microscopic picture of the second nearest neighbor hop, and determine its rate constant.

  13. Rare-earth-gallium-iron glasses. II. Anomalous magnetic hysteresis in alloys based on Pr, Nd, and Sm

    NASA Astrophysics Data System (ADS)

    Cornelison, S. G.; Zhao, J. G.; Sellmyer, D. J.

    1984-09-01

    Giant magnetic coercivity is reported in several metallic glasses of the form (R80G20)100-xFex where R represents Pr, Nd, or Sm, G represents Ga or Au, and 15<=x<=30. An unusual temperature variation of the coercive field is observed showing peaks at intermediate temperatures (~=90 K). In contrast to similar glasses based on heavy rare-earth metals, these glasses exhibit significant chemical short-range order and even phase separation as is shown by the Mössbauer effect and other measurements. The results are consistent with a recent theory which predicts that large coercivity can result from the presence of site-to-site variations in magnetic properties.

  14. The influence of random indium alloy fluctuations in indium gallium nitride quantum wells on the device behavior

    SciTech Connect

    Yang, Tsung-Jui; Wu, Yuh-Renn, E-mail: yrwu@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Shivaraman, Ravi; Speck, James S. [Department of Materials, University of California, Santa Barbara, California 93106 (United States)

    2014-09-21

    In this paper, we describe the influence of the intrinsic indium fluctuation in the InGaN quantum wells on the carrier transport, efficiency droop, and emission spectrum in GaN-based light emitting diodes (LEDs). Both real and randomly generated indium fluctuations were used in 3D simulations and compared to quantum wells with a uniform indium distribution. We found that without further hypothesis the simulations of electrical and optical properties in LEDs such as carrier transport, radiative and Auger recombination, and efficiency droop are greatly improved by considering natural nanoscale indium fluctuations.

  15. MD study of the finite temperature effects on the phase ordering, stacking fault energy, and edge dislocation core structure in elemental Pu and Pu-Ga alloys

    NASA Astrophysics Data System (ADS)

    Karavaev, A. V.; Dremov, V. V.

    2015-02-01

    The Modified Embedded Atom Model (MEAM) of elemental plutonium and plutonium-gallium alloys has been tested for its ability to reproduce the correct ordering of the hcp and fcc phases that is crucial from the point of view of molecular dynamics simulation of elastic-plastic phenomena in the material. Stacking fault energy obtained with the MEAM is in agreement with experimental data. Results of the edge dislocation modeling at the ambient conditions evidence for rather wide dislocation core, namely, 5-6 Burgers vectors. The results of the MD simulation have been compared with those obtained early with recently developed Multi State-MEAM potential.

  16. Catalysts based on activated aluminum alloys. I. A study of copper-alumina catalysts by XPS and deuterium-hydrogen exchange

    SciTech Connect

    Yakerson, V.I.; Subbotin, A.N.; Gudkov, B.S.; Tkachenko, O.P. [Zelinskii Institute of Organic Chemistry, Moscow (Russian Federation); Sarmurzina, R.G. [Institute Metallurgy, Alma-Ata (Kazakhstan)

    1994-09-01

    Surface compositions and electron states of elements in copper-containing catalysts prepared by water treatment of copper-aluminum alloys activated by indium and gallium are studied by XPS. The copper contents in the surface layers of the catalysts is found to be less than that in the bulk. Fast isotopic H{sub 2}-D{sub 2} exchange at 70-200{degrees}C on reduced copper-containing samples and the absence of the exchange on copper-free samples indicate dissociative hydrogen adsorption on copper-containing active sites. The activation energy for the isotopic exchange is essentially dependent on the procedure of catalyst preparation.

  17. Electron beam surface remelting and alloying of aluminium alloys

    Microsoft Academic Search

    P Petrov

    1997-01-01

    This paper reports results of a study of structural and mechanical changes in layers of hypereutectic cast Al? Si alloys as results electron beam remelting and alloying with Fe?Cr powders and followed by electron beam remelting.

  18. Delta/Alpha-Prime Phase Transformations in a Pu-Ga Alloy

    SciTech Connect

    Blobaum, K M; Krenn, C R; Wall, M A; Schwartz, A J

    2005-03-07

    In pure plutonium, the monoclinic {alpha} phase is the equilibrium phase at ambient temperature and pressure. The addition of a few percent of gallium, however, allows the fcc {delta} phase to be retained metastablely at ambient conditions. When the metastable {delta} phase is cooled to subambient temperatures, it partially transforms to the monoclinic {alpha}' phase, which has gallium supersaturated in the lattice. The {alpha}' phase reverts to the {delta} phase when the sample is heated above the ambient temperature. The martensite burst (M{sub b}) and reversion start (R{sub s}) temperatures are functions of the composition, heating rate, and prior thermal history. For a Pu-2.0 at% Ga alloy, the transformation hysteresis is approximately 150 C, which is large compared with other solid-solid phase transformations. Both the forward and reverse transformations are martensitic and proceed via a burst mode. Here, we use differential scanning calorimetry (DSC) and resistometry to perform fundamental studies of the {alpha}'/{delta} transformations with the goal of understanding how aging may affect {delta} phase stability, particularly the M{sub b} temperature. Because materials properties of the {alpha}' and {delta} phases are considerably different (including a density increase of 25% and an accompanying resistivity increase of 46% upon transformation from {delta} to {alpha}'), unexpected transformation to the {alpha}' phase is of particular interest to the stockpile stewardship community.

  19. Optical characterization of copper indium gallium diselenide thin films

    NASA Astrophysics Data System (ADS)

    Hebert, Damon

    Cu(In,Ga)Se2 (CIGS) and its alloys are the leading choice for thin film photovoltaic absorber layers due to their high performance in devices, low degradation, high optical absorption coefficient and high tolerance to off-stoichiometry and intrinsic defects. Film conductivity and recombination losses are controlled by intrinsic point defect concentrations, especially in the near-surface space-charge region of the heterojunction. Despite the amount of research already performed on CIGS alloys, their optoelectronic properties, defect chemistry and recombination mechanisms are still poorly understood. The focus of this dissertation is to optically characterize a selection of CIGS absorber layers fabricated by various techniques in order to better understand the radiative emission and defect physics. This work aims to identify the defects responsible for recombination and their relation to grain boundaries and band edge fluctuations, which limit device performance. This study used photoluminescence (PL) spectroscopy, photoluminescence excitation (PLE) spectroscopy, and cathodoluminescence (CL) to study radiative emissions from a variety of Cu-poor CIGS thin films. Three general types of CIGS films were analyzed. Polycrystalline layers deposited on Mo-coated soda lime glass, polycrystalline layers deposited on metal foil, and epitaxial films grown on (100) and (111) GaAs were analyzed in this work. This work concludes that the donor-acceptor pair recombination model used in most interpretations of CIGS emission should be replaced with a model that accounts for high compensation and band edge fluctuations, which is shown to be undoubtedly the case in Cu-poor CIGS. Within this model, the most commonly observed emissions were explained as free-to-bound types, specifically iii band-to-impurity (BI) and tail-to-impurity (TI) types. Band tail width was measured by PLE. A correlation was established between band tail width and device efficiency. CIGS absorber layers that produced devices of higher performance showed narrower band tails. CL and PL showed an additional deep emission in Na-free films, not present in Na-containing films grown in parallel. It is concluded that most grain boundaries in CIGS act as collection areas for point defects and point defect clusters but also are more or less inactive with respect to recombination due to their built-in electrostatic hole barrier. Spectral and spatial emission characteristics were studied on plan-view CIGS surfaces that were covered with a ˜50 nm thick CdS film by chemical bath deposition (CBD). It is concluded that spectral changes that others have observed in the emission of CdS-treated films is a result of the CBD process itself and not the resulting film or the formation of the heterojunction. The effect of low temperature (˜180°C) air annealing on the emission characteristics of CdS/CIGS thin films was studied by cryogenic infrared and visible PL. Spectral shape was not significantly affected by annealing for either film, but PL intensity did show some dependence on anneal time for both films, which led to an estimate of an optimal time window of 3-10 hours for low temperature annealing.

  20. Origins of unintentional incorporation of gallium in AlInN layers during epitaxial growth, part I: Growth of AlInN on AlN and effects of prior coating

    NASA Astrophysics Data System (ADS)

    Choi, Suk; Jin Kim, Hee; Lochner, Zachary; Kim, Jeomoh; Dupuis, Russell D.; Fischer, Alec M.; Juday, Reid; Huang, Yu; Li, Ti; Huang, Jingyi Y.; Ponce, Fernando A.; Ryou, Jae-Hyun

    2014-02-01

    We propose a new origin of unintentional gallium (Ga) incorporation during the epitaxial growth of AlInN layers. We observed substantial amount of Ga in AlInN layers on GaN-free underlying layers and wafer carrier grown by metalorganic chemical vapor deposition, even though the Ga precursor was not introduced during the growth. The Al(Ga)InN layers were characterized by high-resolution X-ray diffraction and Rutherford backscattering spectrometry. The mole fraction of Ga in the Al(Ga)InN layers showed strong dependence on conditions of the growth chamber, making it difficult to maintain controlled alloy compositions only by growth process parameters. Also, Ga incorporation was not observed under the same growth parameters and conditions, when the indium (In) precursor was absent. The formation of In-Ga eutectic system between metallic Ga from the deposition on the chamber surrounding surfaces and adsorbed In is suggested as a possible pathway for the Ga incorporation. Finally, we performed an intentional chamber coating process prior to growth of AlInN to achieve repeatable Al(Ga)InN growth with stable alloy compositions.

  1. Translating alloy using Boolean circuits

    E-print Network

    Daitch, Samuel Isaac

    2004-01-01

    Alloy is a automatically analyzable modelling language based on first-order logic. An Alloy model can be translated into a Boolean formula whose satisfying assignments correspond to instances in the model. Currently, the ...

  2. Growth of epitaxial iron nitride ultrathin film on zinc-blende gallium nitride J. Pak, W. Lin, K. Wang, A. Chinchore, M. Shi, D. C. Ingram, and A. R. Smitha

    E-print Network

    Growth of epitaxial iron nitride ultrathin film on zinc-blende gallium nitride J. Pak, W. Lin, K the growth of iron nitride on zinc-blende gallium nitride using molecular beam epitaxy. First, zinc-blende Ga electron microscopy is used to reveal the epitaxial continuity at the gallium nitride-iron nitride

  3. Oxidation of tantalum carbide alloys

    Microsoft Academic Search

    É. I. Golovko; L. F. Ochkas; M. S. Koval'chenko; A. F. Nikityuk

    1976-01-01

    1.A study was made of the oxidation of hot-pressed specimens of tantalum carbide, alloys of tantalum carbide with 5, 10, and 15% Ni and 10% (Ni, W), and VK8 alloy in air at temperatures of 500, 600, and 700°C.2.It was established that in the temperature range investigated tantalum carbide and its alloys are superior in oxidation resistance to VK8 alloy.

  4. Utilization of titanium alloy equipment

    Microsoft Academic Search

    N. M. Shmakov; V. S. Mikheev

    1974-01-01

    Alloys AT-3 and AT-6 have wide application in practice in contrast to many series containing titanium alloyed with cheap obtainable elements such as aluminum, chromium, iron, silicon, and boron. Alloys AT-3 and AT-6 are processable. Extruded electrodes consisting of magnesio-thermic titanium and added alloying elements were fused twice in a vacuum arc furnace in an argon atmosphere. After machining to

  5. (Polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

    DOEpatents

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

    2001-01-01

    The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interefere in the ethylene polymerization process, while affecting the the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

  6. Development and evaluation of anode alloys for aluminum/air batteries: Final report

    SciTech Connect

    Macdonald, D.; Real, S.; Urquidi-Macdonald, M.

    1987-02-01

    Experimental and theoretical studies are reported on the development of aluminum alloys for alkaline aluminumair batteries. This work begins by analyzing the thermodyanmics of aluminum in LiOH, NaOH, and KOH solutions as a function of concentration (0 to 7 molkg alkali) and temperature (25 to 100)degree)C). The thermodynamic data define the conditions under which precipitation of Al(OH)/sub 3/ may occur but, more importantly for this study, they yield equilibrium potentials for various charge transfer reactions, including aluminum dissolution, Al(OH)/sub 3/ and A100H formation, AlH/sub 3/ formation, oxygen reduction, and hydrogen evoltuion. These data are used in our mechanistic analyses of aluminum electrodissolution. The findings of this work form the basis of a working model for the activation of aluminum alloy fuels for alkaline aluminumair batteries, in which activation is attributed to the oxidative dissolution of a protective layer of metallic alloying elements (principally gallium) from the surface at a voltage of )approximately)1.5 V (HgHgO). This model is now being used to design and prepare new high energy density anodes for Alair batteris. 29 refs., 87 figs., 39 tabs

  7. PHYSICAL REVIEW A 82, 043806 (2010) Photon self-induced spin-to-orbital conversion in a terbium-gallium-garnet crystal

    E-print Network

    Marrucci, Lorenzo

    PHYSICAL REVIEW A 82, 043806 (2010) Photon self-induced spin-to-orbital conversion in a terbium gradient in the medium. In this work we tested the occurrence of SISTOC in a terbium-gallium-garnet rod in the FI is terbium-gallium-garnet (TGG) which has a relatively high absorption (generally higher than 1000

  8. Experimental heat transfer rates of natural convection of molten gallium suppressed under an external magnetic field in either the x, y, or z direction

    Microsoft Academic Search

    K. Okada; H. Ozoe

    1992-01-01

    The heat transfer rates of natural convection of molten gallium were measured under various strengths of heating rates and three coordinate directional magnetic fields. Molten gallium (Pr = 0.024) was filled in a cubic enclosure of 30 mm à 30 mm à 30 mm whose one vertical wall was uniformly heated and an opposing wall was isothermally cooled, with otherwise

  9. Micromilling of Metal Alloys with Focused Ion Beam-Fabricated Tools

    SciTech Connect

    ADAMS,DAVID P.; VASILE,M.J.; BENAVIDES,GILBERT L.; CAMPBELL,ANN N.

    1999-11-05

    This work combines focused ion beam sputtering and ultra-precision machining as a first step in fabricating microstructure in metals and alloys. Specifically, {approx}25{micro}m diameter micro-end mills are made from cobalt M42 high-speed steel and C2 micrograin tungsten carbide tool blanks by ion beam sputtering. A 20 keV focused gallium beam defines tool cutting edges having radii of curvature < 0.1{micro}m. Micro-end mills having 2, 4 and 5 cutting edges successfully machine small trenches in 6061-T4 aluminum, brass, 4340 steel and polymethyl methacrylate. Machined trench widths are approximately equal to the tool diameters and surface roughnesses (rms) are {approx}150 nm or less. Microtools are robust and operate for more than 6 hours without fracture. Results from ultra-precision machining aluminum at feed rates as high as 50 mm/minute are included.

  10. Metalorganic chemical vapor deposition of GaNAs alloys using different Ga precursors

    NASA Astrophysics Data System (ADS)

    Wei, X.; Wang, G. H.; Zhang, G. Z.; Zhu, X. P.; Ma, X. Y.; Chen, L. H.

    2002-03-01

    The GaNAs alloys have been grown by metalorganic chemical vapor deposition (MOCVD) using dimethylhydrazine (DMHy) as the nitrogen precursor, triethylgallium (TEGa) and trimethylgallium (TMGa) as the gallium precursors, respectively. Both symmetric (0 0 4) and asymmetric (1 1 5) high-resolution X-ray diffraction (HRXRD) were used to determine the nitrogen content in GaNAs layers. Secondary ion mass spectrometry (SIMS) was used to obtain the impurity content. The influence of different Ga precursors on GaNAs quality has been investigated. Phase separation is observed in the <1 1 5> direction when using TMGa as the Ga precursor but not observed when using TEGa. This phenomenon should originate from the parasitic reaction between the Ga and N precursors. Furthermore, samples grown with TEGa have better quality and less impurity contamination than those with TMGa. Nitrogen content of 5.742% has been achieved using TEGa and no phase separation observed in the sample.

  11. Cermet anode with continuously dispersed alloy phase and process for making

    DOEpatents

    Marschman, Steven C. (Richland, WA); Davis, Norman C. (Richland, WA)

    1989-01-01

    Cermet electrode compositions and methods for making are disclosed which comprise NiO--NiFe.sub.2 O.sub.4 --Cu--Ni. Addition of an effective amount of a metallic catalyst/reactant to a composition of a nickel/iron/oxide, NiO, copper, and nickel produces a stable electrode having significantly increased electrical conductivity. The metallic catalyst functions to disperse the copper and nickel as an alloy continuously throughout the oxide phase of the cermet to render the electrode compositon more highly electrically conductive than were the third metal not present in the base composition. The third metal is preferably added to the base composition as elemental metal and includes aluminum, magnesium, sodium and gallium. The elemental metal is converted to a metal oxide during the sintering process.

  12. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter (Houston, TX); Koh, Shirlaine (Houston, TX); Mani, Prasanna (Houston, TX); Ratndeep, Srivastava (Houston, TX)

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  13. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  14. Effect of barrier height on friction behavior of the semiconductors silicon and gallium arsenide in contact with pure metals

    NASA Technical Reports Server (NTRS)

    Mishina, H.; Buckley, D. H.

    1984-01-01

    Friction experiments were conducted for the semiconductors silicon and gallium arsenide in contact with pure metals. Polycrystalline titanium, tantalum, nickel, palladium, and platinum were made to contact a single crystal silicon (111) surface. Indium, nickel, copper, and silver were made to contact a single crystal gallium arsenide (100) surface. Sliding was conducted both in room air and in a vacuum of 10 to the minus 9th power torr. The friction of semiconductors in contact with metals depended on a Schottky barrier height formed at the metal semiconductor interface. Metals with a higher barrier height on semiconductors gave lower friction. The effect of the barrier height on friction behavior for argon sputtered cleaned surfaces in vacuum was more specific than that for the surfaces containing films in room air. With a silicon surface sliding on titanium, many silicon particles back transferred. In contrast, a large quantity of indium transferred to the gallium arsenide surface.

  15. Gallium hydride complexes stabilised by multidentate alkoxide ligands: precursors to thin films of Ga2O3 at low temperatures.

    PubMed

    Pugh, David; Bloor, Leanne G; Parkin, Ivan P; Carmalt, Claire J

    2012-05-01

    The donor-functionalised alkoxides {Me(3-x)N(CH(2)CH(2)O)(x)} (L(x); x = 1, 2) have been used to form gallium hydride complexes [{GaH(2)(L(1))}(2)] and [{GaH(L(2))}(2)] that are stable and isolable at room temperature. Along with a heteroleptic gallium tris(alkoxide) complex [Ga(L(1))(3)] and the dimeric complex [{GaMe(L(2))}(2)], these compounds have been used as single-source precursors for the deposition of Ga(2)O(3) by aerosol-assisted chemical vapour deposition (AACVD) with toluene as solvent. The resulting films were mostly transparent, indicating low levels of carbon contamination, and they were also mainly amorphous. However, [Ga(L(1))(3)] did contain visibly crystalline material deposited at a substrate temperature of 450?°C, by far the lowest ever observed for the CVD of gallium oxide. PMID:22461280

  16. Surface modification of high temperature iron alloys

    DOEpatents

    Park, Jong-Hee (Clarendon Hills, IL)

    1995-01-01

    A method and article of manufacture of a coated iron based alloy. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700.degree. C.-1200.degree. C. to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy.

  17. The electronic structure of indium arsenide/gallium arsenide self-assembled quantum dots in a high magnetic field

    NASA Astrophysics Data System (ADS)

    Awirothananon, Sunida

    The electronic energy levels of dome-shape InAs self-assembled quantum dots (SAQD) grown by the Stranski-Krastanow mode on GaAs substrates are similar to those obtained from a two-dimensional harmonic-oscillator. A simple selection rule allows transitions only that preserve angular momentum, depicted with atomic-like orbital labels s, p, d, f, etc. This electronic structure was examined with photoluminescence (PL) and photoluminescence excitation (PLE) techniques. As well, in magnetic fields up to 28 Tesla applied parallel to the growth direction, SAQD energy-level degeneracies were lifted. The number of branches observed is correlated to the angular momentum. The ground state (GS) level at zero angular momentum is shifted quadratically under the magnetic field and the behavior could be explained with the Fock-Darwin (F-D) spectral model. The effect of annealing at temperatures from 825°C to 900°C in 25°C steps on the SAQD electronic structure was also examined with the PL technique combined with an applied magnetic field in the Faraday configuration. The PL lines were similar to the F-D spectral lines with their degeneracy lifted by the applied magnetic field. These lines exhibited ten (anti-)crossings: three each at 10 T and 28 T, four at 18 T, while the inter-level spacing and the FWHM were reduced with increasing annealing temperature. Thus an increase in the observed (anti-)crossings resulted for the higher anneal temperatures. The in-plane excitonic reduced-mass was inferred from the systematic splitting of the PL p-branches in a magnetic field. The reduced-mass for all the annealed QD samples was about 0.066 m0 +/- 0.012m0 which decreased slightly with anneal temperature. An 8-band k*p model predicted a similar reduced-mass at low alloying of gallium, but an incorrect trend was observed as the alloying increased with annealing temperature. Unrealistic reduced-masses at 50 percent gallium content were reached. This discrepancy is explained assuming the F-D model is a single (independent) bulk particle picture neglecting many-body effects, and also the k*p model assumes identical disks before and after annealing. The SAQDs were in fact inhomogeneous shallow domes whose height is reduced with annealing temperatures. It is an attempt to reduce the effect of many-body interactions such as exchange, configuration and screened coulomb interactions dominant in the PL technique, the PLE technique was use. In this technique, a single level in a collection or 'ensemble' of dots is excited with tuned laser-light and only the Coulomb interactions are assumed to be important. The PLE peaks were found to be blue-shifted relative to PL peaks. Furthermore, under the influence of a magnetic field, two PLE peaks were observed that corresponded to the p and d energy states. However, three 'd' lines were expected and is hypothesized that one of the d lines remained degenerate. Moreover, the carrier dynamics observed in PLE spectra are much more difficult to interpret than that of the PL spectra. Applying the same method, the analysis of the p-branch peaks suggested an in-plane reduced-mass of ˜0.084m0 +/- 0.002m0, higher than obtained from PL measurement. Since the effective mass is normally associated with the mobility of the carriers, this would imply that the excitons in the PLE measurement are less mobile than in PL. This is despite the reduced many-body effects, suggesting that some extra interactions in the PL excitation may actually enhance the carrier mobility. Given the current interest in devices such as QD infrared photo-detectors and the necessary controls on the number of charge carriers in these devices, a single-layer and 25-layer SAQD samples with doping in the top cap layer were compared to un-doped sample using PLE at various detection energies. No absorption signatures appeared for the doped single layer, whereas they were recovered in the 25-layer doped sample. Evidently either dopants or injected carriers diffused into the QD layers beneath the cap. This diffusion and its influence is expected to be decreasing

  18. Thin film gallium arsenide solar cell research. Third quarterly project report, September 1, 1980-November 30, 1980. [Antireflection coating

    SciTech Connect

    Chu, S. S.

    1980-12-01

    The major objective of this contract is to produce gallium arsenide solar cells of 10% conversion efficiency in films of less than 10 micrometers thick which have been deposited by chemical vapor deposition on graphite or tungsten coated graphite substrates. Major efforts during this quarter were directed to: (1) the optimization of the deposition of gallium arsenide films of 10 ..mu..m thickness or less on tungsten/graphic substrates, (2) the investigation of the effectiveness of various grain boundary passivation techniques, (3) the deposition of tantalum pentoxide by ion beam sputtering as an antireflection coating, (4) the deposition of gallium aluminium arsenide by the organometallic process, and (5) the fabrication and characterization of large area Schottky barrier type solar cells from gallium arsenide films of about 10 ..mu..m thickness. Various grain boundary passivation techniques, such as the anodic oxidation, thermal oxidation, and ruthenium treatment, have been investigated. The combination of thermal oxidation and ruthenium treatment has been used to fabricate Schottky barrier type solar cells. Large area MOS solar cells of 9 cm/sup 2/ area with AMl efficiency of 8.5% have been fabricated from ruthenium treated gallium arsenide films of 10 ..mu..m thickness. The construction of the apparatus for the deposition of gallium aluminum arsenide by the organometallic process has been completed. The deposition of good quality tantalum pentoxide film as an antireflection coating has been carried out by the ion beam sputtering technique. The short-circuit current density and AMl efficiency of the solar cells are increased by approximately 60%, with a slight increase in the open-circuit voltage. Details are presented. (WHK)

  19. Size effects in the thermal conductivity of gallium oxide (?-Ga2O3) films grown via open-atmosphere annealing of gallium nitride

    NASA Astrophysics Data System (ADS)

    Szwejkowski, Chester J.; Creange, Nicole C.; Sun, Kai; Giri, Ashutosh; Donovan, Brian F.; Constantin, Costel; Hopkins, Patrick E.

    2015-02-01

    Gallium nitride (GaN) is a widely used semiconductor for high frequency and high power devices due to of its unique electrical properties: a wide band gap, high breakdown field, and high electron mobility. However, thermal management has become a limiting factor regarding efficiency, lifetime, and advancement of GaN devices and GaN-based applications. In this work, we study the thermal conductivity of beta-phase gallium oxide (?-Ga2O3) thin films, a component of typical gate oxides used in such devices. We use time domain thermoreflectance to measure the thermal conductivity of a variety of polycrystalline ?-Ga2O3 films of different thicknesses grown via open atmosphere annealing of the surfaces of GaN films on sapphire substrates. We show that the measured effective thermal conductivity of these ?-Ga2O3 films can span 1.5 orders of magnitude, increasing with an increased film thickness, which is indicative of the relatively large intrinsic thermal conductivity of the ?-Ga2O3 grown via this technique (8.8 ± 3.4 W m-1 K-1) and large mean free paths compared to typical gate dielectrics commonly used in GaN device contacts. By conducting time domain thermoreflectance (TDTR) measurements with different metal transducers (Al, Au, and Au with a Ti wetting layer), we attribute this variation in effective thermal conductivity to a combination of size effects in the ?-Ga2O3 film resulting from phonon scattering at the ?-Ga2O3/GaN interface and thermal transport across the ?-Ga2O3/GaN interface. The measured thermal properties of open atmosphere-grown ?-Ga2O3 and its interface with GaN set the stage for thermal engineering of gate contacts in high frequency GaN-based devices.

  20. Effect of gallium-arsenide laser, gallium-aluminum-arsenide laser and healing ointment on cutaneous wound healing in Wistar rats.

    PubMed

    Gonçalves, R V; Mezêncio, J M S; Benevides, G P; Matta, S L P; Neves, C A; Sarandy, M M; Vilela, E F

    2010-04-01

    This study determined the effects of gallium-aluminum-arsenide laser (GaAlAs), gallium-arsenide laser (GaAs) and Dersani healing ointment on skin wounds in Wistar rats. The parameters analyzed were: type I and III collagen fiber concentrations as well as the rate of wound closure. Five wounds, 12 mm in diameter, were made on the animals' backs. The depth of the surgical incision was controlled by removing the epithelial tissue until the dorsal muscular fascia was exposed. The animals were anesthetized with ketamine and xylazine via intraperitoneal injection. The rats were randomly divided into five groups of 6 animals each, according to the treatment received. Group 1 (L4): GaAs laser (4 J/cm(2)); group 2 (L30): GaAlAs laser (30 J/cm(2)); group 3 (L60): GaAlAs laser (60 J/cm(2)); group 4 (D): Dersani ointment; group 5 (control): 0.9% saline. The applications were made daily over a period of 20 days. Tissue fragments were stained with picrosirius to distinguish type I collagen from type III collagen. The collagen fibers were photo-documented and analyzed using the Quantum software based on the primary color spectrum (red, yellow and blue). Significant results for wound closing rate were obtained for group 1 (L4), 7.37 mm/day. The highest concentration of type III collagen fibers was observed in group 2 (L30; 37.80 + or - 7.10%), which differed from control (29.86 + or - 5.15%) on the 20th day of treatment. The type I collagen fibers of group 1 (L4; 2.67 + or - 2.23%) and group 2 (L30; 2.87 + or - 2.40%) differed significantly from control (1.77 + or - 2.97%) on the 20th day of the experiment. PMID:20445949

  1. Microstructural studies on Alloy 693

    NASA Astrophysics Data System (ADS)

    Halder, R.; Dutta, R. S.; Sengupta, P.; Samajdar, I.; Dey, G. K.

    2014-10-01

    Superalloy 693, is a newly identified ‘high-temperature corrosion resistant alloy’. Present study focuses on microstructure and mechanical properties of the alloy prepared by double ‘vacuum melting’ route. In general, the alloy contains ordered Ni3Al precipitates distributed within austenitic matrix. M6C primary carbide, M23C6 type secondary carbide and NbC particles are also found to be present. Heat treatment of the alloy at 1373 K for 30 min followed by water quenching (WQ) brings about a microstructure that is free from secondary carbides and Ni3Al type precipitates but contains primary carbides. Tensile property of Alloy 693 materials was measured with as received and solution annealed (1323 K, 60 min, WQ) and (1373 K, 30 min, WQ) conditions. Yield strength, ultimate tensile strength (UTS) and hardness of the alloy are found to drop with annealing. It is noted that in annealed condition, considerable cold working of the alloy can be performed.

  2. Alloyed coatings for dispersion strengthened alloys

    NASA Technical Reports Server (NTRS)

    Wermuth, F. R.; Stetson, A. R.

    1971-01-01

    Processing techniques were developed for applying several diffusion barriers to TD-Ni and TD-NiCr. Barrier coated specimens of both substrates were clad with Ni-Cr-Al and Fe-Cr-Al alloys and diffusion annealed in argon. Measurement of the aluminum distribution after annealing showed that, of the readily applicable diffusion barriers, a slurry applied tungsten barrier most effectively inhibited the diffusion of aluminum from the Ni-Cr-Al clad into the TD-alloy substrates. No barrier effectively limited interdiffusion of the Fe-Cr-Al clad with the substrates. A duplex process was then developed for applying Ni-Cr-Al coating compositions to the tungsten barrier coated substrates. A Ni-(16 to 32)Cr-3Si modifier was applied by slurry spraying and firing in vacuum, and was then aluminized by a fusion slurry process. Cyclic oxidation tests at 2300 F resulted in early coating failure due to inadequate edge coverage and areas of coating porosity. EMP analysis showed that oxidation had consumed 70 to 80 percent of the aluminum in the coating in less than 50 hours.

  3. Growth and Characterization of Digitally Alloyed Zinc Oxide Based TCOs

    NASA Astrophysics Data System (ADS)

    Sigdel, Ajaya; Shaheen, Sean; Perkins, John; Ginley, David; Berry, Joseph

    2009-10-01

    Transparent conducting oxides (TCOs) based on substitutionally doped zinc oxide and novel amorphous oxides offer the potential of high performance and low cost for organic solid-state lighting and organic photovoltaic (OPV) applications. We present studies on digitally alloyed amorphous indium zinc oxide (InZnO) with crystalline gallium doped zinc oxide (GaZnO) and zinc tin oxide (ZnSnO3). The films were grown using pulse laser deposition system with varying oxygen pressure. Alternating layers of two constituent materials are deposited with periodicity of around 5 nm. We find that the composite material has similar conductivity as the constituent species grown at similar conditions but the surface roughness and the work function are determined solely by the terminating layer. We observe that both IZO and GZO terminated stacks result in conductivity of 1.5E3 S/cm, but the surface roughness varies from 0.3 nm to 0.7 nm respectively. We also explore other possible combination of zinc based oxide materials in order to optimize the optical and the electrical properties of TCO for possible application in opto-electronic devices.

  4. A comprehensive thermodynamic analysis of native point defect and dopant solubilities in gallium arsenide

    NASA Astrophysics Data System (ADS)

    Hurle, D. T. J.

    1999-05-01

    A detailed analysis of the role of charged native point defects in controlling the solubility of electrically active dopants in gallium arsenide is presented. The key roles of (a) positively charged arsenic vacancies (VAs+) in determining the doping range over which the solubility curve is linear and (b) multiply negative charged gallium vacancies (VGam-) determining annealing and diffusion behavior in n+ material are demonstrated. An equilibrium thermodynamic model based on these concepts is shown to accurately describe the doping behavior of Te, Zn, Sn, Ge, Si, and C and the formation and annealing of the deep level denoted EL2 (assumed to be the arsenic antisite defect AsGa) in melt- and solution-grown crystals. The model provides a much more comprehensive and accurate description of dopant solubility than the widely cited Schottky barrier model of bulk nonequilibrium dopant incorporation. It is unambiguously shown that partial autocompensation of donor dopants by the donor-gallium vacancy acceptor complex occurs for both group IV and group VI donor dopants. The deduced concentrations of arsenic vacancies grown into the crystal during melt growth are shown to be in excellent agreement with values determined by titration and by density/lattice parameter measurements. The obtained data are used to plot the Ga-As solidus. Due to the presence of charged native point defect species (notably, VAs+), the free-carrier concentration at high temperatures is greater than the intrinsic concentration. The calculated concentration is shown to be in excellent agreement with published experimental data. The utility of an equilibrium thermodynamic model in seeking an understanding of doping behavior under conditions of high supersaturation, such as occur with organometallic vapor phase epitaxy and molecular beam epitaxy, is demonstrated. Finally, some suggestions are made as to the likely native point defect equilibria in indium phosphide.

  5. Effect of gallium on growth of Streptococcus mutans NCTC 10449 and dental tissues.

    PubMed

    Valappil, S P; Owens, G J; Miles, E J; Farmer, N L; Cooper, L; Miller, G; Clowes, R; Lynch, R J M; Higham, S M

    2014-01-01

    Gallium-doped phosphate-based glasses (Ga-PBG) were assessed for their impact on Streptococcus mutans and dental mineralisation, firstly by disc diffusion assays followed by biofilms grown on nitrocellulose filter membrane (NFM) and constant-depth film fermentor (CDFF). Short-time exposure (10 min) effects of Ga-PBG on S. mutans biofilm were compared with that of 0.2% chlorhexidine. The effects of Ga-PBG on bovine enamel (which was investigated under pH-cycling condition) and dentine were analysed using transverse microradiography (TMR), profilometry and inductively coupled plasma optical-emission spectrometry (ICP-OES). The disc diffusion assays showed inhibition zones of 24.5 ± 0.5 mm for Ga-PBG compared with controls (C-PBG). Ga-PBG showed statistically significant growth inhibition of S. mutans biofilms on NFM (p = 0.001) and CDFF (p < 0.046) compared with hydroxyapatite (HA) and C-PBG. The CDFF assay revealed a maximum of 2.11 log colony-forming unit (CFU) reduction at 48 h, but short-time exposure effects were comparable with that of 0.2% chlorhexidine only on older biofilms (maximum of 0.59 vs. 0.69 log CFU reduction at 120 h). TMR analyses of the enamel revealed non-significant mineral loss (p = 0.37) only in the case of Ga-PBG samples compared with controls including sodium fluoride. ICP-OES analyses indicated transient gallium adsorption into dentine by calcium displacement. The results confirmed that gallium inhibited S. mutans growth and appears to have the potential to protect the enamel surface under conditions representative of the oral environment. Further work is needed to establish whether it has an application in daily oral hygiene procedures to prevent or reduce caries. PMID:24335164

  6. Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors

    SciTech Connect

    Yang, Jyun-Bao; Chen, Yu-Ting; Chu, Ann-Kuo [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Taiwan (China); Huang, Jheng-Jie; Chen, Yu-Chun; Tseng, Hsueh-Chih [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Sze, Simon M. [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan (China)

    2014-04-14

    In this study, indium-gallium-zinc-oxide thin film transistors can be operated either as transistors or resistance random access memory devices. Before the forming process, current-voltage curve transfer characteristics are observed, and resistance switching characteristics are measured after a forming process. These resistance switching characteristics exhibit two behaviors, and are dominated by different mechanisms. The mode 1 resistance switching behavior is due to oxygen vacancies, while mode 2 is dominated by the formation of an oxygen-rich layer. Furthermore, an easy approach is proposed to reduce power consumption when using these resistance random access memory devices with the amorphous indium-gallium-zinc-oxide thin film transistor.

  7. Pneumocystis pneumonia: importance of gallium scan for early diagnosis and description of a new immunoperoxidase technique to demonstrate Pneumocystis carinii

    SciTech Connect

    Levin, M.; McLeod, R.; Young, Q.; Abrahams, C.; Chambliss, M.; Walzer, P.; Kabins, S.A.

    1983-07-01

    Pneumocystis pneumonia presented in a homosexual with fever, a normal chest radiograph, and pulmonary gallium uptake. Bronchial washings yielded Mycobaterium tuberculosis, but despite antituberculosis therapy he remained febrile, and gallium uptake in the lung increased. Subsequently, silver stain of transbronchial lung biopsy obtained 2 months earlier at the time that tuberculosis was diagnosed showed many Pneumocystis cysts in alveolar spaces. In contrast to Pneumocystis cysts in infected lung tissue from other humans, our patient's Pneumocystis cysts reacted more avidly with antiserum to rat Pneumocystis than with antiserum to human pneumocystis, raising the possibility that organisms that infect humans may have varied surface antigenic properties.

  8. Engineering absorption and blackbody radiation in the far-infrared with surface phonon polaritons on gallium phosphide

    SciTech Connect

    Streyer, W.; Law, S.; Rosenberg, A.; Wasserman, D. [Department of Electrical and Computer Engineering, University of Illinois Urbana Champaign, Urbana, Illinois 61801 (United States); Roberts, C.; Podolskiy, V. A. [Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854 (United States); Hoffman, A. J. [Department of Electrical Engineering, University of Notre Dame, South Bend, Indiana 46556 (United States)

    2014-03-31

    We demonstrate excitation of surface phonon polaritons on patterned gallium phosphide surfaces. Control over the light-polariton coupling frequencies is demonstrated by changing the pattern periodicity and used to experimentally determine the gallium phosphide surface phonon polariton dispersion curve. Selective emission via out-coupling of thermally excited surface phonon polaritons is experimentally demonstrated. Samples are characterized experimentally by Fourier transform infrared reflection and emission spectroscopy, and modeled using finite element techniques and rigorous coupled wave analysis. The use of phonon resonances for control of emissivity and excitation of bound surface waves offers a potential tool for the exploration of long-wavelength Reststrahlen band frequencies.

  9. Molybdenum-based alloy

    SciTech Connect

    Koizumi, H.; Ishihara, H.; Kawakita, K.; Matsumoto, T.

    1984-02-07

    A molybdenum-based alloy improved in mechanical strength and hot workability, which consists of 0.01 to 5.0% by weight of vanadium, 10 to 100 ppm of boron, 10 to 1,000 ppm of carbon, and the balance of molybdenum.

  10. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  11. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong (Pasadena, CA); Johnson, William L. (Pasadena, CA)

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  12. Development of gallium arsenide high-speed, low-power serial parallel interface modules: Executive summary

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Final report to NASA LeRC on the development of gallium arsenide (GaAS) high-speed, low power serial/parallel interface modules. The report discusses the development and test of a family of 16, 32 and 64 bit parallel to serial and serial to parallel integrated circuits using a self aligned gate MESFET technology developed at the Honeywell Sensors and Signal Processing Laboratory. Lab testing demonstrated 1.3 GHz clock rates at a power of 300 mW. This work was accomplished under contract number NAS3-24676.

  13. Local modification of the magnetic vortex-core velocity by gallium implantation

    SciTech Connect

    Langner, Hauke H., E-mail: hlangner@physnet.uni-hamburg.de; Vogel, Andreas; Beyersdorff, Björn [Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany); Weigand, Markus [Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70596 Stuttgart (Germany); Frömter, Robert; Peter Oepen, Hans; Meier, Guido [Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2014-03-14

    The dynamics of magnetic vortices in microsquares with local modifications of magnetic parameters and thickness are investigated. By implanting gallium ions with focussed ion beam into permalloy thin-film elements, we have locally tailored their magnetic properties and the layer thickness. The vortex of the Landau domain pattern of a square is resonantly excited to a gyrotropic motion and crosses regions with and without implantation. With time-resolved scanning transmission x-ray microscopy, we observe an abrupt change in the vortex velocity close to the borders between the two regions.

  14. Effects of Radiation and Long-Term Thermal Cycling on EPC 1001 Gallium Nitride Transistors

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These include radiation, extreme temperatures, and thermal cycling, to name a few. Data obtained on long-term thermal cycling of new un-irradiated and irradiated samples of EPC1001 gallium nitride enhancement-mode transistors are presented. This work was done by a collaborative effort including GRC, GSFC, and support the NASA www.nasa.gov 1 JPL in of Electronic Parts and Packaging (NEPP) Program

  15. Modification of the crystal structure of gadolinium gallium garnet by helium ion irradiation

    NASA Astrophysics Data System (ADS)

    Ostafiychuk, B. K.; Yaremiy, I. P.; Yaremiy, S. I.; Fedoriv, V. D.; Tomyn, U. O.; Umantsiv, M. M.; Fodchuk, I. M.; Kladko, V. P.

    2013-12-01

    The structure of gadolinium gallium garnet (GGG) single crystals before and after implantation by He+ ions has been investigated using high-resolution X-ray diffraction methods and the generalized dynamic theory of X-ray scattering. The main types of growth defects in GGG single crystals and radiation-induced defects in the ion-implanted layer have been determined. It is established that the concentration of dislocation loops in the GGG surface layer modified by ion implantation increases and their radius decreases with an increase in the implantation dose.

  16. Spectroscopy of gadolinium gallium garnet crystals doped with Y b3 + revisited

    NASA Astrophysics Data System (ADS)

    Kami?ska, A.; Brik, M. G.; Boulon, G.; Karbowiak, M.; Suchocki, A.

    2010-06-01

    The optical spectroscopy measurements of gadolinium gallium garnet (GGG) crystals doped with Yb show evidence of the presence of non-equivalent optical centers with very similar radiative decay rates. The energy level schemes of those centers have been determined on the basis of optical absorption, luminescence and Raman experiments. Crystal field fitting resulted in two sets of slightly different crystal field parameters for two non-equivalent Yb centers. Both sets of parameters describe perfectly the experimentally detected Y b3 + energy levels. Correlation between systematic trends in the experimental energy level schemes and crystal field parameters is discussed.

  17. Effects of doping on the geometrically frustrated Heisenberg antiferromagnet Gadolinium Gallium Garnet

    NASA Astrophysics Data System (ADS)

    Silevitch, D. M.; Schmidt, M. A.; Ghosh, S.; Aeppli, G.; Rosenbaum, T. F.

    2011-03-01

    Geometric frustration in the Heisenberg antiferromagnet Gadolinium Gallium Garnet (GGG) gives rise to a set of quantum protectorates where clusters of spins decouple from the overall spin liquid state. At 110 mK, there is a partial transition to an ordered AF state. Here, we examine the effect of lightly doping GGG with Nd ions, which partially alleviates the underlying frustration. We examine the size and binding energy of the spin clusters as a function of doping and temperature, and also characterize the suppression of the Neel temperature as the dopant concentration is increased.

  18. Spectroscopy of gadolinium gallium garnet crystals doped with Yb(3+) revisited.

    PubMed

    Kami?ska, A; Brik, M G; Boulon, G; Karbowiak, M; Suchocki, A

    2010-06-30

    The optical spectroscopy measurements of gadolinium gallium garnet (GGG) crystals doped with Yb show evidence of the presence of non-equivalent optical centers with very similar radiative decay rates. The energy level schemes of those centers have been determined on the basis of optical absorption, luminescence and Raman experiments. Crystal field fitting resulted in two sets of slightly different crystal field parameters for two non-equivalent Yb centers. Both sets of parameters describe perfectly the experimentally detected Yb(3+) energy levels. Correlation between systematic trends in the experimental energy level schemes and crystal field parameters is discussed. PMID:21393800

  19. Electromagnetic excitation of ultrasonic oscillations by yttrium iron garnet films on gallium gadolinium garnet substrates

    NASA Astrophysics Data System (ADS)

    Sarnatskii, V. M.; Mavlonazarov, I. O.; Lutsev, L. V.

    2014-07-01

    We have studied the phenomenon of contactless excitation of ultrasonic oscillations by thin yttrium iron garnet (YIG) films on gallium gadolinium garnet (GGG) substrates upon application of the superposition of a constant magnetic bias field and alternating magnetic field. Dimensional resonance effects that cannot be explained in the framework of existing theoretical notions have been discovered, in particular, in dependences of the amplitude of excited longitudinal oscillations on the YIG film thickness, frequency of ultrasound, and degree of homogeneity and strength of the magnetic bias field. It is suggested that the observed phenomenon is caused by resonant participation of the intrinsic oscillations of domain walls in the excitation of ultrasound.

  20. Differentiation of posterior pararenal space infection from psoas abscess by gallium imaging

    SciTech Connect

    Bose, A.; Mishkin, F.; Delgado, J.

    1983-01-01

    Three of four patients whose cases fit the clinical description of psoas abscess proved on gallium imaging to have infection in the posterior pararenal space sparing the psoas muscle. This space provides a route for spread of infection connecting the spine, the anterior abdominal wall, the scrotum, the anterior thigh, and the gluteal region as demonstrated by the cases presented. Clinical differentiation between posterior pararenal space infection and psoas abscesses is difficult and CT studies may not demonstrate the process when the psoas space is not involved.

  1. Distinctive Signature of Indium Gallium Nitride Quantum Dot Lasing in Microdisk Cavities

    E-print Network

    Woolf, Alexander; Puchtler, Tim; Aharonovich, Igor; Zhu, Tong Tong; Niu, Nan; Wang, Danqing; Oliver, Rachel A.; Hu, Evelyn L.

    2014-01-01

    in Table I. Lasing Statistics Summary Sample Average wavelength of background emission (nm) Average wavelength of lasing mode (nm) Average Lasing Threshold (?W) Threshold Range (?W) QW 446± 2.3 448± 6.7 184 88-375 fQW 457± 3.5 451... and Nanotechnology 5(2): 023001. 6. Someya T, et al. (1999) Room temperature lasing at blue wavelengths in gallium nitride microcavities. Science 285(5435):1905-1906. 7. Holmes MJ, Choi K, Kako S, Arita M, Arakawa Y. (2014) Room-Temperature Triggered Single...

  2. Gallium citrate Ga 67 scintigraphic detection of chronic osteomyelitis in children with leukemia

    SciTech Connect

    Miller, J.H.; Ettinger, L.J.

    1986-03-01

    Chronic osteomyelitis producing unexplained fevers without localizing symptomatology may present difficulty in detection and differentiation in patients with leukemia. Gallium citrate Ga 67 scintigraphy offers a method of detection and localization of both the osseous and extraosseous manifestations of such a process. Once identified, further evaluation by conventional radiographic or sectional imaging techniques may further define the process. We describe three patients with leukemia and unexplained fever in whom occult chronic osteomyelitis was diagnosed by 67Ga scintigraphy, which offers an ideal screening procedure and should be utilized in this clinical setting.

  3. Near-infrared gallium nitride two-dimensional photonic crystal platform on silicon

    SciTech Connect

    Roland, I.; Zeng, Y.; Han, Z.; Checoury, X.; Blin, C.; El Kurdi, M.; Ghrib, A.; Sauvage, S.; Boucaud, P., E-mail: philippe.boucaud@ief.u-psud.fr [Institut d'Electronique Fondamentale, CNRS - Univ. Paris Sud 11, Bâtiment 220, F-91405 Orsay (France); Gayral, B. [Univ. Grenoble Alpes, INAC-SP2M, CEA-CNRS group “Nanophysique et Semiconducteurs,” F-38000 Grenoble (France); CEA, INAC-SP2M, CEA-CNRS group “Nanophysique et Semiconducteurs,” F-38000 Grenoble (France); Brimont, C.; Guillet, T. [Université Montpellier 2, Laboratoire Charles Coulomb UMR 5221, F-34905 Montpellier (France); Semond, F. [CRHEA-CNRS, Rue Bernard Grégory, F-06560 Valbonne (France)

    2014-07-07

    We demonstrate a two-dimensional free-standing gallium nitride photonic crystal platform operating around 1550?nm and fabricated on a silicon substrate. Width-modulated waveguide cavities are integrated and exhibit loaded quality factors up to 34?000 at 1575?nm. We show the resonance tunability by varying the ratio of air hole radius to periodicity, and cavity hole displacement. We deduce a ?7.9?dB/cm linear absorption loss for the suspended nitride structure from the power dependence of the cavity in-plane transmission.

  4. Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon

    NASA Astrophysics Data System (ADS)

    Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Gayral, B.; Brimont, C.; Guillet, T.; Mexis, M.; Semond, F.; Boucaud, P.

    2015-02-01

    We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities ?zxx (2 ), ?zyy (2 ) and the electric fields of the fundamental cavity mode.

  5. A Generator-Produced Gallium-68 Radiopharmaceutical for PET Imaging of Myocardial Perfusion

    PubMed Central

    Sharma, Vijay; Sivapackiam, Jothilingam; Harpstrite, Scott E.; Prior, Julie L.; Gu, Hannah; Rath, Nigam P.; Piwnica-Worms, David

    2014-01-01

    Lipophilic cationic technetium-99m-complexes are widely used for myocardial perfusion imaging (MPI). However, inherent uncertainties in the supply chain of molybdenum-99, the parent isotope required for manufacturing 99Mo/99mTc generators, intensifies the need for discovery of novel MPI agents incorporating alternative radionuclides. Recently, germanium/gallium (Ge/Ga) generators capable of producing high quality 68Ga, an isotope with excellent emission characteristics for clinical PET imaging, have emerged. Herein, we report a novel 68Ga-complex identified through mechanism-based cell screening that holds promise as a generator-produced radiopharmaceutical for PET MPI. PMID:25353349

  6. Analysis of stacking faults in gallium nitride by Fourier transform of high-resolution images

    NASA Astrophysics Data System (ADS)

    Kirilenko, D. A.; Sitnikova, A. A.; Kremleva, A. V.; Mynbaeva, M. G.; Nikolaev, V. I.

    2014-12-01

    We present results of studying stacking faults (SFs) in gallium nitride (GaN) with the aid of Fourier transform of high-resolution transmission electron microscopy (HRTEM) images. Using this method, it is possible both to determine the SF type and to directly measure the corresponding displacement vector. This allowed us to explain the peculiarities of the contrast of HRTEM of structures with high SF density (above 106 cm-1). It is established that the displacement vector component in the (0001) plane in these structures can significantly differ from the expected value of that is typical of single SFs.

  7. Isolated muscular sarcoidosis causing fever of unknown origin: The value of gallium-67 imaging

    SciTech Connect

    Patel, N.; Krasnow, A.; Sebastian, J.L.; Collier, B.D.; Hellman, R.S.; Isitman, A.T. (Medical College of Wisconsin, Milwaukee (USA))

    1991-02-01

    An unusual case of a patient with a long-standing fever of unknown origin (FUO) is presented whose gallium-67 ({sup 67}Ga) images revealed increased activity only in the calf muscles bilaterally. Other imaging modalities also failed to show chest or other abnormal findings. Subsequent biopsy of the right gastrocnemius muscle revealed noncaseating granulomas consistent with the diagnosis of sarcoidosis. When using {sup 67}Ga to evaluate a patient with a FUO, imaging of the extremities should always be included. Also, when abnormal Ga-67 uptake is present in the extremities, sarcoidosis should be included in the differential diagnosis.

  8. IEEE Spectrum: Thin-Film Trick Makes Gallium Arsenide Devices Cheap http://spectrum.ieee.org/semiconductors/materials/thinfilm-trick-makes-gallium-arsenide-devices-cheap[5/22/2010 1:39:13 PM

    E-print Network

    Rogers, John A.

    , such as silicon or glass. Silicon is the stuff of computer chips, but if you want to build the fastest transistor is that compound semiconductors are much more expensive than silicon. A 6-inch wafer of gallium arsenide costs about US $200, whereas a 200- millimeter wafer of silicon goes for roughly $40. So Rogers and his

  9. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon

    2015-04-01

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na2CO3, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na2CO3, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4M HCl, 100°C and pulp density of 20g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. PMID:25769129

  10. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  11. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  12. Preparation of gallium-68 radiopharmaceuticals for positron tomography. Progress report, November 1, 1977-October 31, 1980

    SciTech Connect

    Welch, M.J.

    1980-06-01

    Although the germanium-68 ..-->.. gallium-68 generator is probably the only source of positron-emitting radionuclides that could enable the widespread application of positron tomography, the commercially available /sup 68/Ga//sup 68/Ge generator system suffers from several major disadvantages. The most important of these is that the generator is eluted with EDTA, which forms a very strong chelate with gallium. In order to produce radiopharmaceuticals other than /sup 68/Ga-EDTA, it is first necessary to break the stable EDTA complex and remove all traces of EDTA. This procedure adds several steps and a significant amount of time to procedures for preparing /sup 68/Ga-radiopharmaceuticals. We have developed a new generator using a solvent extraction system which will produce /sup 68/Ga-oxine (8-hydroxyquinoline), a weak chelate. Using this agent we have synthesized several /sup 68/Ga-radiopharmaceuticals and tested them in vitro and in vivo. We have also carried out some preliminary studies to compare generator systems which produce /sup 68/Ga in an ionic form. Attempts have been made using polarographic and chromatographic techniques, and in vivo distribution data to investigate the stability of radiogallium complexes with a series of potentially lipophilic complexing agents.

  13. Anionic Gallium-Based Metal;#8722;Organic Framework and Its Sorption and Ion-Exchange Properties

    SciTech Connect

    Banerjee, Debasis; Kim, Sun Jin; Wu, Haohan; Xu, Wenqian; Borkowski, Lauren A.; Li, Jing; Parise, John B. (Kwangju); (Rutgers); (SBU)

    2012-04-30

    A gallium-based metal-organic framework Ga{sub 6}(C{sub 9}H{sub 3}O{sub 6}){sub 8} {center_dot} (C{sub 2}H{sub 8}N){sub 6}(C{sub 3}H{sub 7}NO){sub 3}(H{sub 2}O){sub 26} [1, Ga{sub 6}(1,3,5-BTC){sub 8} {center_dot} 6DMA {center_dot} 3DMF {center_dot} 26H{sub 2}O], GaMOF-1; BTC = benzenetricarboxylate/trimesic acid and DMA = dimethylamine, with space group I{bar 4}3d, a = 19.611(1) {angstrom}, and V = 7953.4(6) {angstrom}{sup 3}, was synthesized using solvothermal techniques and characterized by synchrotron-based X-ray microcrystal diffraction. Compound 1 contains isolated gallium tetrahedra connected by the organic linker (BTC) forming a 3,4-connected anionic porous network. Disordered positively charged ions and solvent molecules are present in the pore, compensating for the negative charge of the framework. These positively charged molecules could be exchanged with alkali-metal ions, as is evident by an ICP-MS study. The H{sub 2} storage capacity of the parent framework is moderate with a H{sub 2} storage capacity of {approx}0.5 wt % at 77 K and 1 atm.

  14. Testicular toxicity of gallium arsenide, indium arsenide, and arsenic oxide in rats by repetitive intratracheal instillation.

    PubMed

    Omura, M; Tanaka, A; Hirata, M; Zhao, M; Makita, Y; Inoue, N; Gotoh, K; Ishinishi, N

    1996-07-01

    The testicular toxicities of two compound semiconductor materials, gallium arsenide (GaAs) and indium arsenide (InAs), and arsenic oxide (As2O3) were examined in rats by repetitive intratracheal instillation of these substances in suspension twice a week, a total of 16 times. A single instillation dose was 7.7 mg/kg in the GaAs and the InAs groups and 1.3 mg/kg in the As2O3 group. A significant decrease in sperm count and significant increase in the proportion of morphologically abnormal sperm were found in the epididymis in the GaAs group. Especially, abnormal sperm with a straight head increased markedly in this group. In the GaAs-treated rats, there was 40-fold increase in the degenerating late elongated spermatids at the postspermiation stages, stages IX, XI, and XI. From these results, it is indicated that GaAs disturbed the spermatid head transformation at the late spermiogenic phases and caused spermiation failure. InAs caused a sperm count decrease in the epididymis, though its testicular toxicity was relatively weak compared with that of GaAs. As2O3, a probable dissolution arsenic product of GaAs and InAs in vivo, did not show any testicular toxicities in this study. It seems likely that, along with arsenics, gallium and indium play a role in the testicular toxicities of GaAs and InAs. PMID:8812231

  15. Optical properties of gallium oxide clusters from first-principles calculations.

    PubMed

    Rahane, Amol B; Deshpande, Mrinalini D; Chakraborty, Sudip

    2012-11-01

    The optical properties of the (Ga(2)O(3))(n) clusters, with n = 1-10, have been studied within the framework of time dependent density functional theory. The gallium oxide cluster geometries showed evolution from planar configuration (C(2v)) for Ga(2)O(3) to layered globular configuration (C(s)) for (Ga(2)O(3))(10) via corundum configuration (D(3d)) for (Ga(2)O(3))(4). For n ? 5, with the increase in coordination of Ga and O atoms, the polarizability decreases with the size of the cluster. For n ? 6, with the stabilization of average coordination number for gallium and oxygen atoms, the decrease in polarizability is very small. Further, the optical absorption spectra and the corresponding optical gap have been calculated. The overall shape of the calculated spectra strongly depend on cluster geometries. With the increase in size, the discrete spectra of small clusters evolves into quasicontinuous spectra. For n = 10, the spectra show a smooth absorption edge that is a characteristic of the bulk. It is observed that the optical gap oscillate with an increase in the cluster size. The calculated optical gap of these clusters are lower than the band gap of ?- and ?-Ga(2)O(3) phases. The underestimation of the calculated values of the cluster optical gap is due to the use of local density approximation. PMID:23043515

  16. ANALYSIS OF THE WATER-SPLITTING CAPABILITIES OF GALLIUM INDIUM PHOSPHIDE NITRIDE (GaInPN)

    SciTech Connect

    Head, J.; Turner, J.

    2007-01-01

    With increasing demand for oil, the fossil fuels used to power society’s vehicles and homes are becoming harder to obtain, creating pollution problems and posing hazard’s to people’s health. Hydrogen, a clean and effi cient energy carrier, is one alternative to fossil fuels. Certain semiconductors are able to harness the energy of solar photons and direct it into water electrolysis in a process known as photoelectrochemical water-splitting. P-type gallium indium phosphide (p-GaInP2) in tandem with GaAs is a semiconductor system that exhibits water-splitting capabilities with a solar-tohydrogen effi ciency of 12.4%. Although this material is effi cient at producing hydrogen through photoelectrolysis it has been shown to be unstable in solution. By introducing nitrogen into this material, there is great potential for enhanced stability. In this study, gallium indium phosphide nitride Ga1-yInyP1-xNx samples were grown using metal-organic chemical vapor deposition in an atmospheric-pressure vertical reactor. Photocurrent spectroscopy determined these materials to have a direct band gap around 2.0eV. Mott-Schottky analysis indicated p-type behavior with variation in fl atband potentials with varied frequencies and pH’s of solutions. Photocurrent onset and illuminated open circuit potential measurements correlated to fl atband potentials determined from previous studies. Durability analysis suggested improved stability over the GaInP2 system.

  17. Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors.

    PubMed

    Santos, Lídia; Nunes, Daniela; Calmeiro, Tomás; Branquinho, Rita; Salgueiro, Daniela; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

    2015-01-14

    Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 × 10(6), threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm(2)/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping. PMID:25517251

  18. Dynamical and structural heterogeneities close to liquid-liquid phase transitions: The case of gallium

    NASA Astrophysics Data System (ADS)

    Antonelli, Alex; Cajahuaringa, Samuel; de Koning, Maurice

    2013-03-01

    Liquid-liquid phase transitions (LLPT) have been proposed in order to explain the thermodynamic anomalies exhibited by some liquids. Recently, it was found, through molecular dynamics simulations, that liquid elemental gallium, described by a modified embedded-atom model, exhibits a LLPT between a high-density liquid (HDL) and a low-density liquid (LDL), about 60 K below the melting temperature. In this work [1], we studied the dynamics of supercooled liquid gallium close to the LLPT. Our results show a large increase in the plateau of the self-intermediate scattering function (?-relaxation process) and in the non-Gaussian parameter, indicating a pronounced dynamical heterogeneity upon the onset of the LLPT. The dynamical heterogeneity of the LDL is closely correlated to its structural heterogeneity, since the fast diffusing atoms belong to high-density domains of predominantly 9-fold coordinated atoms, whereas the slow diffusing ones are mostly in low-density domains of 8-fold coordinated atoms. The energetics suggests that the reason for the sluggish dynamics of LDL is due to its larger cohesive energy as compared to that of the HDL. [1] S. Cajahuaringa, M. de Koning, and A. Antonelli, J. Chem. Phys. 136, 064513 (2012).

  19. Bronchoalveolar lavage and gallium-67 lung scanning in the evaluation of asbestos-exposed individuals

    SciTech Connect

    Al-Tawil, W.G.

    1986-01-01

    In this study, an attempt is made to evaluate certain parameters that might indicate the beginning of a certain fibrogenic activity in the lung parenchyma, even before such changes become visible on the chest x-ray. The hypothesis is that studies such as certain bronchoalveolar immunological characteristics and Gallium-67 lung scans may be more sensitive indicators of parenchymal lung damage in response to asbestos inhalation than conventional radiographic criteria. If so, then in those cases where the criteria for the diagnosis of asbestosis lack the presence of parenchymal changes, it would be unwise to deny the diagnosis unless further investigation, such as the bronchoalveolar lavage fluid analysis and the Gallium-67 lung scan techniques, are made available. The most significant laboratory parameter for bronchoalveolar lavage, in this study, is that of Neutrophils (PMNs). All three asbestos-exposed groups showed no differences when compared with each other, while such differences were statistically significant when such groups were separately compared with the normal comparison group. A similar finding existed also when the Helper: suppressor T-Cell ratios were compared, and found to be higher in all the asbestos-exposed groups.

  20. Chemical exfoliation and optical characterization of threading-dislocation-free gallium-nitride ultrathin nanomembranes

    NASA Astrophysics Data System (ADS)

    ElAfandy, Rami T.; Majid, Mohammed A.; Ng, Tien Khee; Zhao, Lan; Cha, Dongkyu; Ooi, Boon S.

    2014-11-01

    Semiconductor nanostructures have generated tremendous scientific interests as well as practical applications stemming from the engineering of low dimensional physics phenomena. Unlike 0D and 1D nanostructures, such as quantum dots and nanowires, respectively, 2D structures, such as nanomembranes, are unrivalled in their scalability for high yield manufacture and are less challenging in handling with the current transfer techniques. Furthermore, due to their planar geometry, nanomembranes are compatible with the current complementary metal oxide semiconductor (CMOS) technology. Due to these superior characteristics, there are currently different techniques in exfoliating nanomembranes with different crystallinities, thicknesses and compositions. In this work we demonstrate a new facile technique of exfoliating gallium nitride (GaN) nanomembranes with novel features, namely with the non-radiative cores of their threading-dislocations (TDs) being etched away. The exfoliation process is based on engineering the gallium vacancy (VGa) density during the GaN epitaxial growth with subsequent preferential etching. Based on scanning and transmission electron microscopies, as well as micro-photoluminescence measurements, a model is proposed to uncover the physical processes underlying the formation of the nanomembranes. Raman measurements are also performed to reveal the internal strain within the nanomembranes. After transferring these freely suspended 25 nm thin GaN nanomembranes to other substrates, we demonstrate the temperature dependence of their bandgap by photoluminescence technique, in order to shed light on the internal carrier dynamics.